All eyes, or lack thereof, were on Tenebris' "corpse", wondering if Mettaton was just seeing things and the stress of everything that's been happening was making them go insane. After watching for a bit longer, his hand twitched again, causing Alphys to squeal in fright while Sans lit up his eye; he didn't know what trickery to expect.

What shocked them even further was when Tenebris suddenly moaned. "Ugh… could someone tell me why I feel like I'm lying on nothing? Am I floating? Is this hell, or just a wide expanse of nothing?"

Sans slowly deactivated his eye as he stared in disbelief. "T… Tenebris?"

"Oh, is that you Sans? You never told me you had shortcuts to the afterlife. Would have been nice to know."

Mettaton got a closer look at the human and noticed why he was acting like he was still dead… or acting like he passed on. "DARLING, PERHAPS YOU SHOULD TRY OPENING YOUR EYES."

This apparently startled the human. "Wait, who's there? And what do you mean- " Tenebris opened his eyes and saw Alphys, Sans, and Mettaton looking at him with shocked faces. "Hold on… I thought I died…?"

Sans continued to stare in disbelief… before slowly starting to laugh. "I have no idea how you managed to pull that off, but you did. That acting was very convincing, Tenebris."

This baffled the human. "What are you talking about, Sans? I legitimately thought I died, yet… I'm still alive?" He got up, but frowned when he put his hand on the floor. "Alphys, is your floor some kind of magic tile that has no temperature?"

Now it was everyone else's turn to be baffled. Alphys slowly shook her head. "N-no… my floor sh-should be cold…"

Now Tenebris was panicking a little. "D-did I lose feeling in my hands? Can someone tell me what's going on?!"

Alphys and Sans looked at each other while Mettaton started something up on his body. Sans shrugged. "Your guess is as good as ours, buddy. We legit thought you died, so when you started moving again, I thought you staged it."

"Why would I stage my death in this serious a situation? I think there's better things to accomplish than pretending to be dead."

"I THINK I JUST FOUND OUT WHY YOU CAN'T FEEL." Everyone looked at Mettaton, who shuddered. "DR. ALPHYS INSTALLED MANY THINGS ON MY BODY, INCLUDING VITAL SIGN SCANNERS. I REGRET TO INFORM YOU… THAT YOUR BODY HAS CEASED FUNCTIONING."

Alphys looked shocked, then confused. "You're saying he's still technically dead, even though he's awake and talking to us right now?"

"EXACTLY. THE CLOSEST PARALLEL I CAN DRAW IS THAT HE'S AKIN TO A ZOMBIE NOW, LIKE IN ONE OF YOUR ANIMES, ALPHYS."

Tenebris looked at his hand in shock before beginning to laugh. "Guess that explains why I'm not feeling any pain right now. Despite me… still being able to speak, and listen, I'm technically supposed to be dead. Guess that makes me a "dead man walking"."

Despite what was going on, Sans burst into laughter and both Alphys and Mettaton let out a chuckle. "IF YOU CAN LOOK ON THE BRIGHT SIDE OF THINGS, DARLING, I DON'T THINK YOU REALLY HAVE TO WORRY ABOUT ANYTHING. I'M METTATON, BY THE WAY."

"Tenebris. Nice to meet you." He looked around for a bit before his eye fell on the monitor, which made him panic. "Wait, forget about me! What about Undyne?!"

Alphys gasped and rushed over to the monitor… just in time for Frisk to strike a finishing blow against the undying heroine, causing the scientist to cry out in grief. "Damn it... so even THAT power... it wasn't enough...?" Sans' eyes grew dark; he didn't feel the world reset during that skirmish, meaning that the kid managed to beat her without resetting ONCE.

Tenebris, despite not feeling it, clutched his hand tightly with renewed rage and hatred. "That bitch…"

Undyne started laughing as her body slowly melted. "If you think I'm gonna give up hope, you're wrong. Cause I've... got my friends behind me. After all, Alphys told me she would watch me… and if anything went wrong, she would evacuate everyone else… she will also have called Asgore and absorbed the six human souls we already have… with that power…" She gives one large grin. "THIS WORLD WILL LIVE- "

She was cut off when a dark orb suddenly started approaching her. Tenebris immediately recognized it. "That's the orb I summoned in a panic when Frisk took out my eye! What is it- "

Undyne absorbed the orb and the area exploded with darkness, catching Frisk off guard. When the darkness began to dissipate, she looked and saw Undyne's silhouette, no longer looking like it's melting. She spoke with a slightly dark echo in her voice. "This power… I can tell this is Tenebris' power. So he left something to help me, intentionally or not, did he?" She let out a somewhat maniacal laugh. "He must really hate you for what you've done. Who am I to deny this power? Now… you may have defeated me twice, but this time… things will be different!"

The dark mist fully cleared and everyone saw Undyne's new look. Her armor, formerly black, was now a dark purple with meaner spikes coming out of it. The red heart-shape on her front was now black and depicted with spikes coming off its sides. Mettaton let out a whistle as the dark warrior engaged Frisk again. "WHO KNEW SHE COULD GAIN SUCH A BOOST FROM SOMETHING CONSIDERED AN ACCIDENT. TENEBRIS, DARLING, YOU MUST BE FAR MORE POWERFUL THAN YOU LET ON."

"I need to get back to her regardless of that!" Tenebris gritted his teeth. "That little bitch needs a double helping of pain!"

He was about to run out when Sans teleported in front of him. "Buddy, let Undyne handle her. This may sound odd, but I believe that she can deal out enough punishment on her own." Looking at Alphys and Mettaton, he continued, "Besides, I think we can refine those dark powers of your even further and I want to see how far you can go."

Tenebris looked between Sans and the monitor before sighing. "Alright, I'll go with you. However, I think we should remove what's left of my right eye; at this point it's just going to be an eye-sore." He paused for a second before chuckling a bit. "Unintentional pun."

Mettaton let out a sad sigh. "AND HERE I WAS THINKING I WOULD BE ABLE TO INTERVIEW YOU, POSSIBLY THE WORLDS FIRST SENTIENT ZOMBIE. OH WELL, I'LL JUST HAVE TO MAKE DO."

After getting his eye removed so that it was just a socket now, something that made Alphys extremely squeamish, Tenebris and Sans went back to Snowdin. Upon getting there, Sans let out a sigh. "Alright, buddy. I'm going to be very honest with you about something… that might make you call me insane."

Tenebris raised an eyebrow. "Me being something akin to a ghoul is already insane as it is, but I'll humor you."

Sans sighed again. "Well… I'll be blunt; I know Undyne won't be able to handle that kid in the end, even with her new burst in power. Before you say anything, I didn't want to state that in front of Alphys; she looked hopeful that Undyne could pull through this time."

"What makes you so certain? Surely you would believe in one of your friends to do something like that?"

"Normally, I would since it would mean I don't have to do anything. However, that kid… is special. Do you know the concept of RESETTING?"

Tenebris mulled over it for a bit. "The only way I know of it is in video games, typically when you start a new file over an old one. Basically, you erase all of your progress to play the game from the beginning, save for instances of new game plus."

Sans looked down at the ground, dark thoughts clearly in his mind. "That sounds accurate… far too accurate for my liking. That kid? She is capable of doing just that."

Tenebris stood there for a few moments to process it before adopting a horrified look. "Y-you mean… she's done this before?!"

"More than likely. How do you think she beat Undyne in her Undying form? Even with her upgrade to The Dark Undying, because that kid can RESET, it won't matter in the end. Even if she's killed, she'll just reset to an earlier point in time and try again; with full memory of everything from before."

"So… she chose to use that power just to kill everything, huh?" Tenebris began trembling with rage. "If I had that power, I would try and use it for good! But nooooo… she has to treat these innocent lives like playthings in her twisted GAME."

Sans looked down. "Because of that, I don't think Undyne will be able to kill her in the- " both skeleton and undead felt the world suddenly shift. "Looks like you're immune to small resets like that one, huh?"

Tenebris merely growled. "That's good. That way, she will never be able to learn any "attack patterns" if I ever get the dubious pleasure of skewering her. Speaking of, I'm willing to bet that's the reason why you were able to instantly teach me everything I currently know and why everything seems so familiar down here."

"Exactly and while I'm aware she might know my attacks as well, I'm going to try and extremely annoy her into quitting and resetting later on." This was punctuated by another RESET shift.

"Wait, you're not going to try and do that now?! Is it purely because your lazy… or…?"

Sans chuckles a bit. "So your ability to see someone's true face still hasn't changed, huh? Anyways, while I might be lazy, maybe she might just not be completely evil and won't kill every monster down here. If not… well… she's gonna have a bad time."

Tenebris nodded. "Regardless of what happens, I'm going to be helping you no matter what you say. Still, have you pinpointed what allows her to reset?"

"DETERMINATION…"

Tenebris mulled over it before growing a wicked smile. "Alright… then I suppose she's going to know… just what true fear really is."

"Sounds like you've got a thought in your mind. However, with regards to your magic, you've yet to learn everything. Before you only got up to intermediate level and it served you just fine then. Now, I think you will need everything at your disposal if you want to get anywhere."

Tenebris was about to say something when he was cut off by Selendis suddenly saying in his mind, "W-what's going on? Why am I in Tenebris' body?!"

Tenebris suddenly had a flat look on his face, earning a confused look from Sans. "Selendis? You're awake?"

"T-Tenebris, what's going on? How am I in your mind?"

"Well… long story short, I somehow managed to absorb your soul to co-exist with mine and… well I died later on, but we still exist in this body despite it no longer functioning."

"S-so we're like a zombie now?"

"Or something close to it. I really don't care in the end, though. It means I can still get some justice from that little- "

"Wait, no! Please don't kill my sister!"

That gave Tenebris even more pause before he growled in irritation. "Why?! She's murdered so many innocent people, she's murdered ME, and most of all she murdered her own sister! How can you- "

"I… I know defending her like this makes no sense. But please understand; that's not Frisk! The Frisk I know would never even willingly HURT anyone, let alone kill!"

How can you be so certain? For all either of us know, she's kept up that façade for god knows how long!"

"I've still known her longer than you and I can tell you now: it's not her and never will be!"

Tenebris let out a growl before Sans finally spoke up. "Okay, buddy, why do you look like you're having an internal conversation with yourself?"

Tenebris shook his head. "Oh, Selendis just came to… and is currently trying to convince me not to kill Frisk…"

That got a flat look from the skeleton. "Doesn't she realize just how much pain and suffering that kid has inflicted on us?"

"It's under the context of "that's not her"."

"Well it isn't! Please… you have to… you have to believe me!" Even in his mind, she was already growing desperate.

Tenebris opted to ignore her for now and stumbled a bit from yet another "RESET shift" before asking, "So are we going to start the advanced training now?"

"May as well; who knows how long Undyne will hold out in her new form. Just warning you now: this will be unlike anything you've done so far. Be ready for a grueling exercise."

Tenebris snorted and shook his head. "Need I remind you that I can't feel ANYTHING, even pain? I still have emotions, thank god, but my physical senses outside of hearing and sight are out of my scope."

Sans raises an eye socket. "Sounds inconvenient. Can't even tell if you picked up something properly or not since you can't feel it. Even still, perhaps It'll help you in the long run."

Tenebris nodded, continuing to ignore Selendis' pleas in favor of his rage as the world is rocked by another RESET shift. "Helpful or no, we need everything we can get. Let's get right down to figuring out what else I can do with my magic."

Thus, Tenebris began refining his dark magic to its greatest potential thanks to Sans still managing to remember what was in that book about the magic of darkness. Eventually, Tenebris had mastered his darkness completely including, but not limited to, being able to split off shadows to fuse with someone else's shadow allowing for two-way thought communication, create more than just shadow claws over his hands and arms, create dark portals anything can go through, shadow weaving which he used to repair his clothes, and the ability to turn his now-deceased body into pure shadow to move around and possess someone's soul directly.

He also managed to summon a new type of weapon. It starts off as a single-edged broadsword, but it can extend into an enormous scythe for additional reach and coverage. While he wasn't able to master the broadsword mode of this weapon, he was proficient with the scythe mode due to what Sans gave him in terms of memories.

During the training, Selendis never stopped pleading to Tenebris to not hurt or kill her little sister, that Frisk was being controlled by some outside force. Even after she learned of Frisk's ability to RESET, she was still firm in that belief. While Tenebris couldn't let go of his hatred at first, Selendis' insistence and kindness began to replace it with doubt and worry. What forced Frisk to change so suddenly?

At one point during the training, Sans had stopped dead in the middle of training, causing Tenebris to stop with a confused look. "Why are you stopping?"

"Ah… it seems your supposedly "empty" eye socket now has something in it." Seeing Tenebris' baffled look, he sighed and approached while bringing out a hand mirror. "Probably best if I gave you a mirror for you to see for yourself."

Tenebris took the mirror with an even more confused look before looking into it. What he saw surprised him: He still had his black and purple left eye, but now there was a green heart in his right eye socket. "Wait, since when did that happen?!"

"I was about to ask the same thing… hold on, I can see out of it, though you're still the one controlling it."

Tenebris shrugged. "I suppose it'll, at the very least, allow you to see what's going on." Seeing Sans' baffled look he elaborated, "Selendis can see through my right eye now, for some reason."

Sans thought for a moment before making the two souls appear. Despite there being a green heart in Tenebris' right eye, Selendis' green soul appeared with Tenebris'. "Perhaps it's a side effect of your mastery over darkness. Very interesting and curious…"

Tenebris hummed for a bit before realizing something. "Hey Sans… when was the last RESET?"

Sans thought for a moment before his eyes grew dark. "A while. Don't tell me the kid learned her new attack patterns already. Let me check something; be right back." With that he disappears. Tenebris stood alone in the snow-0covered fields of Snowdin before he came back. "Bad news, Undyne has fallen for the third and final time. Alphys went through with the evacuation, though unfortunately some monsters didn't get the memo and are still scattered throughout Hotland and the Core, easy prey for that kid."

Selendis let out a whimper in the back of Tenebris' mind; she desperately wanted to believe that it was something other than her dear little sister who was doing this. Tenebris gave a worried frown. "Shouldn't we try to evacuate them as well?!"

"I hate to admit it, but it's already too late for them. Besides, I kind of want to keep your continued existence in this plane a secret from the kid since she thinks you're dead."

Tenebris sighed, no longer filled with the hatred to get angry over it. "So… we just sit and wait?"

"Sadly, yes. However, since it will take the kid some time to get through Hotland and the Core, I want to introduce you to Asgore, our king down here." Sans was about to teleport the both of them when a thought crossed his mind. "Say, why don't you try using your portals to get there? You just learned how to make them, so maybe it's a good way of getting around."

Tenebris pondered it before nodding. "Guess it's worth a shot. Can't rely on you all the time to get me around after all."

Selendis let out a sigh. "Why do I get the feeling it won't work out the way we want it to?"

"Hopefully that's not the case, but I'll be prepared for failure in that event."

Tenebris focused for a bit before summoning his "broad-scythe" weapon and literally cutting open a portal that seemingly leads into darkness. Sans raised an eye socket. "Why did you have to use your weapon?"

"Portals I summon without doing this are not very big as of this point without being inefficient. Also, can I ask you to stay here in case this doesn't work like we think it will?"

Sans thought for a bit before nodding. "Alright, I'll give you five minutes. If you're not back by then, I'll assume you're at the capital."

Tenebris nods before jumping in and having the portal close behind him. When he looked around, all he saw was swirling purple darkness everywhere; darkness he could use if he ever drags an opponent into here. Selendis noted his thoughts on that subject. "If that's the case, this is more like a pocket dimension than a portal. I don't think this will get us anywhere."

Looking around for a bit more, Tenebris nods. "I think you're right. Oh well, it was worth a sho- "

("DARK… DARKER… YET… DARKER…")

Tenebris jumped when he heard a ghastly voice come from the darkness. He summoned his weapon and looked around cautiously until he saw what looked like a skeleton in a black suit with a line coming from each eye socket; one going up and the other going down. "W-who are you?"

The skeleton seemingly ignored the undead human. ("THE DARKNESS KEEPS GROWING.") This began freaking out both souls. ("THE SHADOWS CUTTING DEEPER… PHOTON READINGS NEGATIVE…") The figure suddenly looked at Tenebris with what was actually a soft smile. ("IN RETROSPECT… IS THAT NOW… NECESSARILY A BAD THING?") Approaching Tenebris, who was now staring with wide eyes, the figure bowed. ("DO NOT BE AFRAID, YOUNG ONE, FOR I AM NOT YOUR ENEMY.")

Tenebris sputtered a bit before saying, "H-how did you get here? This is the first time I've… ever been here. Has this place been here the whole time?"

The skeleton looked surprised. ("YOU CAN UNDERSTAND ME? CURIOUS… PERHAPS THIS DEMENSION IS HAVING THIS EFFECT. TO ANSWER BOTH YOUR QUESTIONS, THIS DIMENSION… DIDN'T EXIST UNTIL YOU CREATED A PORTAL TO THIS PLACE. WHEN IT WAS CREATED, I FELT MYSELF DRAWN INTO IT, ALLOWING ME TO FINALLY COLLECT MY ENTIRE BEING INTO ONE PLACE. I AM W. D. GASTER, FORMER ROYAL SCIENTEST OF KING ASGORE.")

Tenebris bowed, though he was still shaky. "I-I'm Tenebris. W-what do you mean by "collecting your entire being"?"

("I'VE NOT THE TIME TO EXPLAIN. AS SUCH, I WANTED TO TELL YOU ONE THING: YOUR DARKNESS IS THE ANSWER TO STOPPING THE GENOCIDE PERMANENTLY IN THIS TIMELINE; THE FORCE THAT CAN TRANSCEND ANOTHER. SOON, THE CHOICES OF ONE HUMAN AND ONE FLOWER WILL DETERMINE WHETHER THIS TIMELINE WILL DECAY OR THRIVE.")

Tenebris was confused when Selendis said, "Is he talking about stopping Frisk?!"

Shakling his head, the undead human asks, "What do you mean by my darkness stopping the genocide permanently? Are you saying I can stop the RESETS?"

("YES… AND NO… YOU WILL UNDERSTAND WHEN THE TIME COMES. UNTIL THEN, YOU NEED TO GO BACK; JUDGEMENT WILL SOON BE HELD.") Tenebris was about to respond when the figure disappeared. Letting out a small sigh, he re-opened the portal and hopped back out. When he was gone, Gaster reappeared with his soft smile. ("AND THANK YOU FOR BEING SO KIND TO MY SONS….")

When Tenebris hopped out of the portal, he found himself back in Snowdin… and in front of a very startled Sans. "Buddy, you were only gone for a second. Guess the portal idea is a no-go, huh?"

Tenebris and Selendis frowned physically and mentally respectively. It felt like they were in there for at least five minutes. "No it isn't. All my portals lead to what I think is a pocket dimension that I somehow created. A veritable "world of darkness" as some people may call it."

Sans let out a sigh. "You are full of surprises. Regardless, guess we'll have to take one of my short-cuts to the capital; I don't know how much time we have until the kid gets there." With that, he grabs Tenebris' arm and they suddenly find themselves in a long hall with orange light filtering through. "Go on and meet the king. I'll wait here for the kid."

Uncertainty in both his mind and Selendis', Tenebris continued through the nearby door where the both of them felt a sense of déjà vu wash over them. This was especially so when they found a monster watering the flowers in the throne room. "Oh? Is someone there?"

Tenebris bowed nervously despite the king not looking. "Y-your majesty, I've come seeking an audience with you."

Turning around, Asgore said, "But of course. What did you need to- " He took as step back when he saw the undead human. "Well… I suppose if you… requested an audience, I can't say no to even a human."

"Former human, actually." Seeing the confused look on Asgore's face, Tenebris clarifies, "I've technically died, your majesty, and I continue to live on in a body that has ceased functioning. As such, I'm technically a walking corpse."

"A walking corpse? Can it be… can I see your soul?" Tenebris hesitated before nodding and exposing his soul. A look of realization spread across Asgore's face. "That explains it and also explains why you somehow managed to absorb another human's soul. Your soul has been infused with so much magic of a particular element, in this case shadow, that you've become part elemental."

Tenebris frowned. "That's why?"

"Indeed. In fact, I'm surprised your body isn't collapsing, or on the verge of doing so. While humans could use magic back before monsters were sealed underground, they couldn't hold large quantities like us monsters due to their physicality being very restraining to magic without suffering negative effects. Yet here you stand, a veritable bottomless well of magic."

Tenebris shook his head. "Good to know, but that's not why I'm here. There's… something in the underground slaughtering monsters and is the reason why I wanted an audience with you! Has Alphys called you to tell you to- "

Asgore let out a soft laugh. "To absorb the six human souls? I don't think the situation's that urgent." The prompted a look of disbelief from the undead; is this guy really that clueless?

"He's not lying!" Both Tenebris and Asgore look to see a small flower on the ground with a face… and a pleading one at that. "T-that human has been slaughtering everyone down here and… she's coming here!"

Tenebris frowned, wondering why both him and Selendis has some slight animosity towards this flower before ignoring it. "If my words aren't enough, then perhaps… what's your name?"

"F-Flowey the flower!"

"Perhaps Flowey's words can convince you? This isn't something we would joke about, Asgore!"

Asgore frowned before sighing. "It's not that I don't believe either of you. It's just that… I'm still missing one more soul. Absorbing the other six right now would force us to start all over again."

Flowey shook his head vigorously. "Better to start over than to die!"

Asgore let out a sigh. "If I recall correctly, Sans is supposed to hand out judgement to anyone coming to this place. That skeleton may be lazy, but he's one monster nobody should cross; despite not taking hits well, he can dole out punishment in spades."

Tenebris frowned before sighing. Asgore didn't seem like he was going to budge an inch on this. "If… that's how you feel… Flowey, see if you can't still convince him. I… need to check on Sans…"

Subconsciously, he knew Sans wouldn't let him fight with him, but he needed to be there to observe if Frisk really is under some third party's control. Heading back to the orange hall, he separated a shadow to merge with Sans' so that he can talk to him with thoughts. With that, he melded into the shadows to be inconspicuous and waited.

On the other end of the hall, Chara saved before a dimensional box with a smile. Despite this being her third attempt at genocide and trying to force Frisk into selling her soul, the second time with Selendis, Frisk's older sister, didn't change much. This time, however, Tenebris had left behind dark energy when he died. She had no problem with Undyne the Undying, but even she was caught off guard when the energy fused with the melting warrior and made her into something even stronger.

Chara welcomed it. It was "something new" and she enjoyed it immensely. In fact, she was disappointed that nothing else new like that happened during her genocide.

In the back of her subconscious, she recognized Frisk and how quiet she's been ever since they killed Papayrus, Selendis, and finally Tenebris. She merely laughed at the girl as she faced a shadow she's seen twice already. "Time for round number three, you comedian."

For those of you wondering, think of Tenebris' new weapon as something similar to Ragna's Bloodscythe from Blazblue.