AN: Warning: Young Gaster was a bit unstable growing up though he mellowed out with age. So Yes, there will be some creepy Gaster in here (Even if it's unintentional).

Omake: Where Did It Begin?

W.D. Gaster PoV

Prologue

A piece of writing that is found at the beginning of a literary work, before the first chapter, and separate from the main story. In other words, the beginning of a story. But the question is:

Where does our story begin?

Was it the moment Monsters were first Sealed underground? The Fall of the First Child? The start of a foolish plan that led to the Deaths of Chara and Asriel Dreemur?

The Slaughter of Six Innocent Child? A misplaced step leading into a tumble into the Core? The Fall of the Seventh Child named Frisk, who held the Soul of Determination?

Does our story begin with a stick or a knife? Does it start at a handshake or when a dusty tab is thrown in an empty bar resisting without a ghost town? Did it truly begin when an old Flame is dosed for the last time or when Harry Potter breathes his first?

Or did it start somewhere else entirely?

How about before the war? At a moment in time when a young, recently orphaned skeleton monster discovers a dying ember of a flame in the ruins of what once was the home of thousands of Elemental Monsters.

Yes, this...This is the start of our story.

Not the war, not the fallen children, or the countless but this...

This right here, this moment in time, is right where EvErYtHiNg truly begins. For you see, that young Skeleton monster trying to Heal a dying ember was me and the young elemental passed out in my arms -like some damsel in distress- is the one that will one day be known as Grillby.

This is the moment we first met.

This is the moment I first saved a life and this is the moment that drove us into becoming the monsters we one day would be known throughout all the underground and across several Multiverses as.

This was the moment that would shape reality as we knew it.

Not that we knew it then. Matter of fact, it was something we wouldn't catch onto for thousands of years to come.


Omake: Mine

W.D. Gaster PoV

As a child, I had always been lonely. Too smart for other monster children to understand, too young for monster adults to connect to, too different for humans to accept.

Nothing I did ever seemed to matter and sometimes just made my isolation worse- The Monster Children became scared of me, the adults thought I was strange, the humans thought I was a demon given physical form- and it didn't help that went my parents died I couldn't even bring myself to cry.

Why would I?

They had just been strangers passing through my life but never staying long enough for me to reach them, but people didn't see it that way and my isolation became worse.

I tried to 'fix' myself- to be what they wanted me to be, to act how they wanted me to act- but it was all in Vain. Nothing I did would ever satisfy them, so I stopped trying.

For the longest time, I was lonely. No one and nothing in my dull word could ease the pain that tore at my soul and slowly drove me mad...

Then I found it. The cure I had been looking for all these years:

A dying ember in the ruins of a village.

It was so small, so scared, and in so much pain.

It needed someone, anyone, to help it or it would perish and I... I was the only one ThErE. It was PeRfEcT- as if God himself had set up this moment just for me- and I was cruel as all my soul could feel was happiness at its misery.

It was hard to keep the smile off my face as I worked on trying to save the elemental toddler's life, but it wasn't easy as the other's soul was damaged. It was unstable and fading in and out of life and death like a drunk walking down a cobblestone street.

"I can help you," I told them as my eye light glowed a shade of green, "but I need you to trust me and bring forth your soul."

They hesitated- not that I expected anything different considering what I was asking- but it was easy to talk a scared child into seeing things your way with a few gentle words of reassurance and soft hands of bone. And like I promised:

I fixed them. I made the pain go away, I made the fear vanish, I drove away Death itself...And I did it all by binding the core of their soul with a shard of my own.

Sure, there were other ways I could have saved him- ways I probably would have used in other timelines- but I chose this way for a reason. For you see by doing things this way, I had bound us together in mind, body, magic, and soul. I had made myself a vital part of his life as without me, he would die as his soul would unravel without my piece to hold him together.

He was TrApPeD.

Though he didn't know that...

The villagers I lived with, on the other hand, did and were horrified by my actions. Some of them started blaming themselves for some reason, but I couldn't understand why. I had saved him and now I wouldn't have to be alone anymore:

It was a Win-Win as far as I was concerned.

They did not agree. Instead, they tried TaKiNg HiM fRoM mE.

I...I didn't want to hurt them.. I never wanted to hurt anyone, but they left me no choice. They were trying to throw me back to the loneliness. They were trying to StEaL the one God himself had led me to.

I couldn't let that happen...

After all, he was MINE.


Omake: The Dangers of Resets

Grillby's PoV

It was unraveling.

With each reset, with each death, his soul came more and more undo as the piece holding it together at its core strained against reality itself.

He was...He was dying, but that was nothing new.

What truly worried him was the piece of soul holding his together as the only way it could be unraveling like it was, was if **** was dying within each reset as well... That was impossible...

Right?

****** couldn't leave the ****. The door in Waterfall wouldn't let him out and there was no other entrance or exit and as long as he was inside ****** was practically immortal...So why was that piece unraveling further and further with each reset?

"..."

He doesn't have an answer and he hasn't seen the other in a while, so he's had no chance to ask, all that he knows is something has gone wrong.

Even as he thinks the thought the world shifts around him in the tell-tell signs of a reset...A glance downwards shows exactly what he expected to see:

His Soul had unraveled a bit further.

He's unsure exactly how many more Resets his Soul can take, but he doesn't care about himself. Instead, he just prays he doesn't drag ****** down with him.


Omake: Loop

W.D. Gaster's PoV

It wasn't supposed to be like this.

He wasn't supposed to die and stay dead.

He was supposed to Reset as all the others did. He was supposed to reappear in the safety of his bar-He had left the void and killed the human himself just to ensure it- but he doesn't...Not this time.

Throughout the Underground, word spreads of a monster who has gone missing. They search high and low, through every tunnel and crack in the underground kingdom, but Gaster knows it's all in vain.

They will not find him.

Grillby was beyond their reach now.

Frowning to himself, purple eye lights glance down at the soul imprisoned in his magic even as it unraveled into nothing more than basic coding only to reform again and repeat the process over, and over, and over, and over again.

The body, just beneath the soul's cage, followed its soul's example: Bright Flames, Dim Flames, Dust, Bright Flames, Dim Flames, Dust, Bright Flames, Dim Flames, Dust... Again and Again, both Soul and Body repeated its never-ending pattern of Life and Death.

It was Hell to watch, but Gaster owed him that much seeing as he trapped the other into said Hell.

Either way, he wouldn't have to watch much longer as he had an idea that would fix all of this if it worked.


Omake: Grand Theft Coding

W.D. Gaster PoV

Repairing a Soul wasn't easy, especially one with damage Coding as each individual strand of coding that formed a place, human, monster, ectra...was unique... So when trying to repair one you needed to be A.) A God or B.) A Master Coder specializing in Bullshiting The Universe into believing everything you Code is actually reality.

Thankfully, Gaster was good at Bullshitting his way out of situations: How else was he supposed to escape the Void to battle the Murderous Child before they could have a chance to erase everything?

Another thing you needed when trying to repair damage coding, was Coding itself, but not just any Coding but Special, Unique, One of a Kind Coding...

And he knew exactly where to get Said Coding. Resisting the Urge to Crackle, the Skeleton vanished into the darkness of the Void.

*One Destroyed Timeline Later*

If Chara was honest, the ghost child couldn't help but feel proud of herself as she finished presenting the 'options' to a dust-covered Frisk as she waited for the power she could only access after a complete genocide to surface.

Erase or True Reset.

The power of Gods. The Power to destroy realities and words alike...Hehe...Hehehehe... And it was all Their's. They had earned this power and with it, they would rule over all of reality just as Frisk once promised them..

...

...

...

Any Second now.

...

...

...

*A note falls on the floor beneath you. It is written in Wing-Dings Font. Translate in process...*

Dear Chara and Frisk,

You're Grounded.

The Power to control Worlds and Realities are now payment for the Crimes against both Monster Kind and Humanity. Not to worry though, I'll see it put to good use.

-WDG

PS. I would duck if I was you.

"Wha-"

BOOM!

"Holy Shit! What the Fuck are all those Gaster Blasters doing here?!"

*CRACK. You're HP has reached 0. *

GAME OVER


Omake: The Many Issues of Sans the Skeleton

Sans PoV

Sans the Skeleton had many issues ranging from both little ones everyone knew about to enormous ones he dared not to breathe. For example:

Issues Number One: That sock.

The one sock in the living room that no matter how many times he had picked up somehow always ended up right back there.

Due to that, Papyrus thought him too lazy to pick up his own socks, but Sans had picked it up hundreds of times- Hell, he had even burned it one, and Gaster Blastered it out of existence a dozen times over- only for it to reappear back in its usual spot. After a short investigation, he discovered the issue was due to someone having removed the coding that allowed the sock to be moved...

For some reason, he has the strangest urge to save Gaster only to shove his Father back into the Void himself.

Issue Number Two: A homicidal creature pretending to be a human that controlled time and space just so it could trap all of the Underground into its little 'game'

...Did he really need to explain that one?

Issue Number Three: The Nightmares caused by said time traveling, homicidal creature pretending to be human.

Again. Does he need to explain?

Issue Number Four: Mettaton

That glorified tin can kept flirting with his brother and was heading themself headfirst into a Bad Time if they didn't stop while they had a chance.

And finally, Issue Number Five: Grillby

Everyone knew Grillby was a friend of his, but not many were aware of just how long the two had known each other thanks to Gaster's fall into the Core. Though no one else remembered it, Sans could recall a time he was a baby bones being taken care of by the Flame Monster. He could recall the other cooking him meals, playing games with him, and drowning him in their care and attention.

Was it any surprise his younger self had been head over heels with someone who had been so loving to him?

Then Gaster disappeared and without Gaster, there couldn't be a Grillby, yet somehow there was. Grillby seemed to remember they were living with him and freaked out when they didn't come home- he had been too scared to and dragged Papyrus along with him- before proceeding to tear the Underground apart in his desperate search for them.

Once they were old enough, Sans had bought himself and Papyrus a new home in Snowdin and had been welcomed with open, but rather distant, arms from everyone but Grillby. Grillby hadn't changed how he treated them much besides treating them as equals instead of a kid in stripes.

Then the Creature fell and the loops started. Sans found himself slowly losing his mind, so was it any surprise he went and spilled everything to the one being who he trusted above all others?

...Hehe, Grillby probably thought he was insane but the flaming bartender never sent him away and spent more time looking after him and Papyrus while keeping an eye on the kid in every loop he told the other the truth.

Then the loops reset, so he told Grillby the Truth again, and again, and again...Until eventually when he went to tell the other, Sans discovered there was No Grillby. The Elemental Monster had just vanished into thin air and unlike when he and Papyrus had been missing baby bones:

Sans never did find Grillby when he tore apart the Underground in his search.


Omake: Multiversal Meetings

Harry Potter's PoV

If he was honest, Harry Potter liked to believe he was willing to put up with a lot of nonsense for the sake of those he considered his family. For example:

Falling into the Underground and leaving that Monsters and Magic were real.

A talking, soulless flower which either had a crush or wanted to outright kill him for how many times the teenager had accidentally stomped on him.

The fact it was Snowing underground...SNOWING. That shouldn't be possible and blaming magic for it was bullshit. He still wanted a proper answer on how that was happening.

Being haunted by a skeleton who accidentally erased himself from all of time and space. Then meeting said Skeleton's son, who told just as horrible puns as his Father, and then said son's brother...That one was a Cinnamon bun and officially needed all the protection the Universe had to spare.

Learning his Nibbling was being hunted by a vengeful ghost who wasn't actually as evil as everyone first believed, but rather desperate to gather back the broken shards of their brother's soul. The shard that had apparently been absorbed by all Monster Kind and the only way to get them back was to murder every monster and grab the shards before their souls could shatter...

Which lead him to a new issue: Appearantly, his younger Nibbling was able to control the space-time continuum and abused said power to murder countless monsters in the name of 'Fun' while their ghostly companion tried to grab the shards of their brother's souls...Only to find one piece of the soul was still missing as it had gone missing with a monster by the name of Grillby and his Nibbling still kept killing because 'they could'.

...

...

Yeah, Harry was willing to put up with a lot of bullshit, but this...

This right here was crossing a line.

You see, after God knows how many resets, Harry- in a moment of weakness- had finally permitted Sans the Skeleton into talking him into sharing his bed and it was officially the best sleep Harry had ever had in his life. Despite being made of bone, Sans made a wonderful stuffed animal. Especially after having another mental breakdown and the other had a habit of purring in his sleep, so he was perfect for a Cuddle Buddy.

Only...

Well... You see, it would have been a perfect night had he woken up still inside Sans bed instead of on a cold, concrete floor surrounded by skeletons that looked a great deal like his Sans and Papyrus while his Skeleton partner still out cold beside him.

"A Human?"

One of them questioned with Sans voices...And holy shit, that one looked exactly like his Sans with the blue hoodie, eternal grin, round head, and the distant smell of ketchup.

Slowly emerald eyes moved from the Sans look alike to a Sans that appeared to have gone goth and started a love affair with Mustard behind Ketchup's back and finally a Papyrus in a hoodie that smelled suspiciously like weed and honey. After a moment, his eyes flickered away from the three and down at His Sans...

Wait a moment, why were there three sets of feet underneath the blanket?

Feeling a sense of dread, Harry lifted a corner of the blanket and... Yep, there was His Papyrus as well, cuddled up into his Sans' side so his face was hiding in the blue fabric of his brother's hoodie.

Slowly his gaze moves from his skeletons to the three staring at him with empty eye sockets, then back at the two under the covers with him, then the three once one, then back.

'It WoUlD aPpEaR wE hAvE tRaVeLeD tHrOuGh ThE mUlTiVeRsE.'

"Human," The Sans look-a-like speaks in a tone that spells a Bad Time is just around the corner and though it's nothing physical, Harry could practically feel his 'Shits left to Give' thread snapping inside his skull.

No. Absolutely not.

Harry had been willing to put up with a lot of bullshit for the sake of his Friends and Family, but this right here crossed a line.

"Nope," he speaks firmly causing the three to jerk back in surprise as he settles himself next to Sans free side, "Nope. Nope. Nope. I am not putting up with this bullshit, Sans."

He throws the cover over all three of their heads and half pray it will somehow make him and his Skeleton Brother's reappear back in their Sans' bed.

"Err...Human?"

"No."

"But-"

"No."

"I-"

"I said Fuck Off, Sans!"

There's a soft noise like a Papyrus' laughter, but Harry can't find it within himself to care. After all, Sans had promised him a nice, peaceful rest- No Soulless Flowers, No Time Loops, No Ghost, No Crazies waiting to either kidnap or kill him at a moments notice, and Murderous Nibblings- and by the Stars Above, Harry was going to get it one way or another.


Omake: Multiversal Meetings- Lie

Sans PoV

Dread was a familiar emotion to Sans the Skeleton- better known as Magi now- but never before had he felt such a thick buildup of its form within his non-existent guts.

For while they were on the surface, They were not safe.

Especially Harry.

For you see, it turns out his Grillby wasn't the only one to go missing. Instead, Every Grillby across the Multiverse had disappeared all at once- but only his returned even if it was in a new form- and not even a month later a creature made of pure darkness had surfaced.

This Creature, according to the others, devoured Souls- those of humans and monsters alike- and its sole weakness appeared to be Light itself... It doesn't take a genius to assume that this creature was somehow linked to the disappearance of the Grillby's-...Grillbi?- especially when one took in the timing of its arrival and their disappearance.

And then those look-a-like Monsters start asking about His Grillby.

These desperate Monsters are asking about His Grillby....It doesn't take a Scientist to figure out exactly what's going on here or why they were even asking at all:

Soul Devouring Creature of Darkness + Light as a weakness = Grillby would be the perfect weapon against it... Only their Grillby's have disappeared...And though they don't know it, his is The Mage they attacked down in the basement.

Sans has little doubt in his mind that if they learned the truth they would try to recruit or guilting Harry into helping them which in turn would endanger the emerald-eyed teen...Not that they would care... If they were like his Pre-Harry self, all humans could drop dead and they wouldn't bat an eye as long as there wasn't a speck of monster dust amongst the corpses...To them, Harry would be nothing but an expendable pawn to further their and Monster Kind's own Survival...

And well, that's something he can't permit. EVER.

Judging from the look Papyrus grants him, the other also had come to the same conclusion and are both in agreement on what has to be done. So, with an easy smile, Sans turns his attention back to his and his Brother's counterparts and does what he has always done best:

He lies to himself.

"Sorry Pal, Our Grillby Dusted years ago."


Special Omake:

What if Grillby/Harry was reincarnated into another universe entirely only to be drought back to the Undertale Universe once older?

AN: This is an Omake idea between myself and Red Sova while I was visiting the other in the hospital. (No, they don't have the Virus. They're just an idiot who decided they no longer needed their medication and ended up collapsing due to it. Their family Doctor is now holding them 'captive' until their partner returns from their business trip.) So if they ever posted an idea like this: No, it was not stolen as they helped create it.

So in this one, we chose the Fallout Universe. More specifically Fallout 3 and Fallout New Vegas as Personally I like to think the Lone Wonderer and The Courier are the same person, just later on in their life. If this was the case, Harry/Grillbys LV would probably end higher than 50 and seeing how Fallout 4 doesn't have a level cap... Harry's stats would actually be LV100. If not higher.

With LV like that Red and I came to an agreement that Harry probably wouldn't even make it two steps outside of the Ruins before Sans blasted him into oblivion, but what if they had a special ability like Frisks Reset that let them conceal their LV. So instead of Harry Potter LV 100 (+), their stats would show Harry Potter LV 1.

Then another thought came to me, in the Fallout universe you have the options of Continue, Load, and New Game when you die...So doesn't that kind of act like Frisks resets? What if Harry still had these abilities in the Undertale Universe? This would also explain how Harry remembers resets he also has the ability.

I personally thought that idea was Grade A material, but then Red throw out a new idea: What if Frisk was from The Fallout Universe and came to the Undertale Universe while an infant in the same accident-Maybe something happened to them in Big MT? - that sent our character there, but was somehow the two were separated while transversing Universes?

Or better yet, What if these two weren't separated at all? What if Frisk really did accidentally fall into the Underground? Maybe while going whatever child does and disobeying orders to stay away from the Mountain? And what if they always Reset because each time they reach the surface their Brother Figure is always missing by the time they return to the surface?

So that leaves us with a question: What happened to The Harry/Grillby/Lone Wonderer/The Courier? Well, Frisk doesn't have a clue, but they'll keep resetting for as long as it takes to find them. Then they get the idea to try different routes in hopes maybe changing things would bring the other back and by doing so open themselves up to corruption.

Now a twist: What if one day, after thousands of Resets and failures to find Harry; they do a True Reset... Only this time, when they wake in the Flower Bed in the Ruins, they're not alone. After thousands of Resets, Harry/Grillby is now in the Underground.

To Be honest with you, I was good with letting things drop here. I mean we practically created a Fallout AU of 'The Trail We Blaze' between the two of us, but Red... Well, Red is a creative Genius at times and while I wish I could claim this idea, I cannot.

What is this idea?

What if Chara tried possessing Harry/Grillby when he appears in the new True Reset Timeline?

To be honest, I didn't quite understand where Red was going with this in the beginning. I mean, Chara already had Frisk who controlled basically was an immortal child due to their control over the timelines.

Why would they want a new 'partner'?

First of all Chara, like Frisk, had been corrupted due to the amount of LV gained over the timelines, but unlike Frisk, their LoVe doesn't vanish with each new Reset.

Instead, it stays and it adds up, but no one notices due to the fact they have an ability that, like Harry, allows them to hide their LV under a False Stat.

Secondly, For Chara, this is something New and New is always fun.

Thirdly, Chara may be tired of only gaining partial control over a body, and here was a brand new body just waiting for someone with the right mindset to take control and live a life this person obviously didn't want. Come on, this is a Cursed Mountain which people only climb to die or because they're foolish children and everyone knows it. So it's not that much of a stretch for Chara to assume this person was trying to commit suicide and accidentally got caught in the TimeLine. Chara wanted a body of Their own and this person obviously didn't want to live so it was a Win-Win in their opinion.

And if somehow this was an accident and this person wanted to live...Well, Chara is a Corrupted Ghost with high loVe and A Soul of Determination and this person...

They weren't.

In Their opinion, A hostile takeover would be a piece of cake and they could just boot out the other being in the body and take it as their own.

Now imagine this:

*Frisk and Harry are unconscious since it's the start of a New TimeLine. Chara is the only one awake. *

Chara *acting like a child on a sugar high at the thought of having their own body and the Fun they and Frisk would have since they both would have their own bodies and share control over The Timeline. And therefore wasting no time to eagerly jump inside what they see as their future body with the full Intention of booting Harry and his Soul from his own body.*

Chara *reappears a moment later screaming as a hand clutches their rear as they fly across the room and crashes face-first into a stone pillar at the sheer force and speed that if you blinked you would miss it. *

*Chara then proceeds to crash to the ground in front of the pillar into a lumpy pile with their rear sticking in the air. And right in the center of the back of their shorts in the Visible imprint of a boot.*

That's right. Chara tries to possess Harry so they can boot him out and steal his body for their own. Only to be booted out themselves. But how?

Did Harry himself do it? Gaster? Maybe even some concept of Grillby still self-aware within Harry's Mindscape?

The answer is both a simple and complicated one:

Chara cannot possess Harry because Harry is already possessed. That's right, Harry is possessed, but it's not by Gaster like I myself personally thought.

So who?

The answer is none other than Ulysses, from the Fallout New Vegas DLC: The Lonesome Road.

Now, this opens up a whole new route for the AU as everyone who has played The Fallout 3 DCL knows who Ulysses is, why he called you there, and what he's trying to teach you. But for those who don't you should check out this link:

wiki/Ulysses

As you can read for yourself, as The Courier we did something we probably shouldn't have and Ulysses 'holds the Courier responsible for the destruction of the place that he believed could have been his true home.'

But that doesn't sound anything like our brother Harry/ Grillby does it? In the 'Trial we Blaze', I wrote Harry to be a quiet, kind of naive, Protective Older Sibling to Frisk...But what if this Harry wasn't always that way?

What if, when he first left the Vault and discovered his powers over the Space-Time Continuum; Harry fell into the same trap as Frisk? Harry had the power of a God in the Fallout Universe (Waiting would be more like fast-forwarding time, Load Game to jump back in time, New Game would be Reset, and Mods/Console Command would be like Overwrite) so he could do whatever he wanted and no one would really stand a chance against him...And if he doesn't like the way it plays out...Well, he can always start a New Game.

So Harry wasn't always the kind, naive, protective older brother Frisk once knew. Instead, he got to the point he becomes so horrible and out of control that the Wasteland knew him as 'Devil'...

This would be where Ulysses would stage his intervention to teach his Fallout Cannon lesson about actions having consequences. But this time there would be a catch because unlike the rest of the Wasteland:

Ulysses could remember each Gameplay/Reset Harry did.

That's right: Ulysses is the Judge of the Fallout Universe which kind of makes me believe his Souls would be a mixture of Bravery and Patients because let me honest: Not many people are willing to stand up to someone they know has God Like abilities, but he does anyways. And unlike Frisk with Sans countless attempts, Harry actually listens when the other decides his life needs an intervention.

Thus a Reset, which that in itself must have been hard for Harry as Resets take you to The Beginning and unlike Frisk, Harry's beginning isn't falling down a hole into the Underground. Rather it's his literal First Breathe taken in life followed swiftly by Death of Catherine aka His Mother.

Unlike Frisk, Harry has to Relive His Whole life if he Resets.

Only this time, When Harry/Grillby is forced to flee the Vault. Ulysses is waiting for him outside. (Because let's face it, something differently went wrong in this kid's life of a place like the Wasteland considered him a Devil...And well, Ulysses' not wrong. Harry's life kind of went to hell real quick:

His Father abandoned him.

His Uncle figure (Jonas) was murdered.

All except for one security officer wants to kill him.

He had to kill people, for the first time in his life, just to not be killed himself.

His best friend, in the end, chooses the safety of the vault instead of leaving with him like she originally claimed she would.

He's locked out of the Vault, the only place he's known his whole life, and into a world he's not prepared for as he literally has nothing but a 10 mm pistol, the clothes on his back, and whatever he shoved into his Pip-Boy.

And then there's the Wasteland itself and all its inhabitants.

What Harry needed upon leaving the Vault was a Therapist of someone who could help guide him. Instead, he had feral beast, ghouls, raider, enclave soldiers, eyebots, DeathClaws, Radiation, super mutants, slavers, extra, extra...So is it any wonder a teenager would fall down that slippery slope upon discovering their God Like abilities? )

Therefore Ulysses, instead of being a campfire companion like in Cannon, becomes a Real Companion and travels the Wasteland with Harry/Grillby while trying to research the other the concept of morals...It works a bit too well as over time the Former 'Devil' becomes 'The Messiah', which Ulysses sees as another ego boost capable of sending right back down that slippery slope.

Personally, I like this idea and not just for the mental image of Ulysses literally kicking Chara's ass out of Harry's Head/mind/body (He went through a lot of effort repairing this kid and ensuring they didn't become some lunatic with a God Complex to lose them to some ghost with a God Complex), but because of how it paints Harry. With this Harry is painted with a sense of mortality and experiences massive character building as he struggles to rebuild himself from the ruin he allowed himself to become.

By falling into the same trap as Frisk, Harry shows that he is only human and fully capable of making mistakes. He's not this untouchable, unreachable, perfect older brother, but someone who has to learn through his own mistakes. This would also help him connect to Frisk later on since he knows exactly what Frisk is going through since he himself went through it before.

And it's not just Harry who would experience character building, but Ulysses as well since their conflicting Character, morals, and personalities would sometimes clash in a way that would force them to compromise on a solution instead of following just one 'right' way. And seeing how these two would be traveling together through all of Fallout 3 and NV, they would learn to coexist and care for each other while picking up one another habits. (I kind of feel bad for Ulysses once Harry's magic kicked in)

Which makes the ending all the more tragic.

Remember, Harry is Possessed by Ulysses (who is content to be an unseen observer) which means at this point in time, Ulysses is Dead. Somewhere along the line, Ulysses dies and instead of moving on, chooses to hunt Harry. To make this even more tragic, Red suggested making it so Ulysses dies protecting Harry from something (we haven't decided on what yet) which would probably traumatize Harry.

So you're probably wondering if Ulysses died why didn't Harry just load a Save?

Well, in The Fallout Games there's a concept called AutoSave, which the game saves itself after massive achievements or a set period of time. So what if this happened to Harry? Ulysses died and before he could load a Save file, the autosave overwrote it?

I suggested maybe Harry reset and try to avoid Ulysses death, but it was cut down quickly. For while Resetting might work temporarily, it won't solve the end problem, because even with the powers of a God there are such things as fixed periods of time. An example of these would be:

Gaster falling into the Core

The Death of Chara and Asriel.

The birth of Flowey.

The Destruction of the Divide.

The Death of Catherine at Harry's Birth.

James suicide to protect Project Purity.

Being kidnapped by aliens, etc...

Some things can't be changed, even with a reset and Ulysses' Death just so happens to be one of them. Resetting would only buy them more time together, but eventually, Ulysses himself would put a stop to it.

We proceeded to make it so that at some point before he arrives in the Undertale Universe, Harry becomes aware of the fact Ulysses is haunting him to make up for all the pain we would probably put him through in that arc.

Somehow this conversation brought us back to Frisk and a whole new idea was born:

What if Frisk is the Cloned offspring of Harry and Ulysses created in a form of Thanks by Dr. Möbius (Old World Blues DLC) after misunderstanding their relationship.

Sure these two could probably be in a romantic relationship, but I think they would be like brothers after traveling together for so long. And after they save Big Mountain (and the wasteland) from the Think Tank, Dr. Möbius- believing their relationship romantic due to how close they are due to the number of resets they lived through together- created them a child to complete their family.

This child was Frisk.

After Ulysses' death, Harry is left as the other person there for Frisk, but Harry himself doesn't know how to be a parent. So he tries being their older brother instead by following the example Ulysses set for him.

Frisk has no idea of their true parentage as Harry never told them. He's always claimed to be their Brother and has done his best to be just that.

This idea has a lot of potential since there are so many ways to run with it, but my favorite suggested one was to make it so Frisk always had these silent issues about never being good enough and believing their parents abandoned them and Harry because of them and making it so they never find out the truth unless they kill Harry in a Genocide Run and discovered an item on his remains which would tell them the Truth Harry couldn't bring himself to.