Previously: Deos, Frisk, Toriel and Flowey have arrived in Waterfall, a moist and water filled part of the underground, a place where Undyne, Captain of the Royal Guard is waiting for them, meanwhile Cali and Dr. Alphys tell each other what they've been hiding from everyone, Cali with granting a perpetual nightmare coma to those that were enslaved by a demon and Dr. Alphys by turning those she thought that she had previously saved into twisted amalgamations of what they were. They both cried their eyes out after they did this...

(Deos' Apartment)

Dr. Alphys has been crying for a while now, once Cali was sure that she had stopped, she dared to speak "Feel better now, Alphys?"

"Y-Yeah...you must hate me now..." Dr. Alphys said with self-loathing in her voice. "If you d-do, I don't b-blame you."

"I'd have to hate myself, If I was to do that, we had good intentions with what we did, but they want badly wrong, we didn't know how others would react, so we kept it to ourselves, so that we didn't have to answer for our actions, it worked...but the guilt, the anger and the self-hate was killing us, the truth has to come out...for both of us." Cali said.

"S-So, we should tell all of those that need to?" Dr. Alphys asked.

"Not at first, let's start with the person that we're each closest to, we both know who yours is, you'll need her to support you through what happens next." Cali said, a little more cheerfully.

"B-But..." Dr. Alphys said with a strong amount of anxiety.

"Look, Alphys...I know I might sound like a pain in the tail, but you need to tell her, if she still likes you after that, you'll make her a very happy girl by telling her how you feel and maybe...something else." Cali said, a bit more playfully near the end.

This made Dr. Alphys blush with embarrassment, she caught herself thinking of dirty thoughts.

"I have a confession of my own to tell Deos..." Cali said.

Dr. Alphys then decided to get some payback "So you're going to tell him how you feel about him?"

"N-no!" Cali said nervously.

"You need to know for sure, Cali." Dr. Alphys said, Cali twirled one of her pigtails around her finger as she thought about this.

"Let's wait until he's reached Hotland, Okay, now what's happening to our two humans and flower?" Cali asked.

"Okay...thank you for being understanding, Cali." Said Dr. Alphys.

(Waterfall)

The journey through waterfall was mostly without incident, Frisk had their first glimpse of Undyne, who was receiving the daily report from Papyrus, who told her that the human eluded him (which wasn't wrong) but then the conversation grew darker and they overheard that she was going to hunt them down herself and Papyrus decided to help out any way that he could, she thought that she saw Frisk in the seagrass briefly and readied a magic spear, but then she decided that no-one was there and then melted into the shadows, the same Monster Kid was excited at seeing Undyne and walked ahead. They then engaged in a flexing contest with Aaron, a...seahorse monster with arms, which made him flex away from the immediate area, after some more puzzles using the bridge seeds, Frisk, Deos, Toriel and Flowey found themselves faced with an expanse of water.

"I don't think that this raft will support all of us, bye bye Frisk!" Flowey said with indifference.

"That won't be necessary, I can float over the surface while carrying you Flowey, as for Toriel...she's not physically there, she's in the Dimension Pocket Amulet, so her weight won't be an issue." Deos said.

Frisk used the raft to get across and Deos used his magic to float across while carrying Flowey, they then walked along the wooden path, Frisk offering to carry Flowey for now and Deos offering to hold onto the Dimensional Pocket Amulet.

"How close is this Undyne, that dangerous looking Captain of the Royal Guard?" Toriel asked.

This was answered by a magic spear in front of Frisk, Undyne was waiting for them.

"Everyone, meet the sushi chef's nightmare!" Deos said, less than subtly.

She then fired three at once at them, Deos used his magic dampening gauntlet, which made them dissapate, much to the surprise of Undyne.

"That's some strong counter-magic...why are you protecting this human?" Said Undyne.

"Because they have done nothing wrong." Deos replied

"HOW CAN YOU SAY THAT?! IT'S A CRIME THAT THEY'RE STILL LIVING AND BREATHING!" Undyne shouted

"If life is a crime, then we should all be dead...have you heard of any reports of dead monsters, any piles of white dust? No, what you have here is a human that has done no wrong to monsterkind, a human who's a complete pacifist." Deos said, Frisk nodded in agreement, Flowey was getting annoyed with all this talking.

"NGAAAAAHHHHHHHHHHHHHHHHH!" Undyne screamed, as she jumped at Deos, this was something that he didn't prepare for.

"Run, Frisk." Deos said, Frisk nodded and ran while holding Flowey as Undyne hit Deos onto the floor with bone crunching force, she cracked a couple of his ribs, making him lightly scream in pain. With this nuisance out of commission, she turned her attention to Frisk and Flowey, she's able to use her spears again, but just as she's about to throw them, she receives a jolt to the back, just enough to disrupt her casting and to get her attention.

"What?! You want more?" Undyne said, mockingly.

Deos' voice now had a lot of rage in it "You could've heard us out! We could've dealt with this peacefully! But then you had to jump into action and break a few bones, just when you couldn't do something more STUPID..." His physical form is rippling, as if an unknown force inside him had been awakened. "You decided to threaten a child! Human or monster, it wouldn't matter to me what they were, I can't allow you to do that. It would seem that you're too THICK-SCALED...to be open to diplomacy! So I'm going to have to teach you that lesson the hard way!" Deos screamed, who's voice echoed around the nearby area as a bright light flashed in front of her, in front of her is an unmasked Deos in an armored form of his own with a red heart on his chest plate, he is more muscular than he was, his hair is more...spiky and his eyes are black with white irises and he will not stand for Undyne's actions any longer, his voice was more echoey "Now you'll have to face the wrath of DEOS THE DETERMINED!"

Undyne can't believe what she's seeing in front of her, another human...who can use magic and is now a powerful opponent, she took off her helmet to reveal that she is a fish-like monster with red hair done in a ponytail and an eyepatch around her left eye, her mouth is lined with piranha-like teeth that was open mouthed at this sight, which quickly turned into a menacing smile. "AWESOME! I knew anime was real!"

"BAD. Choice. Of. Words." Deos the Determined said in a grave voice as he generated a red mace construct to match Undyne's spear construct, he was ALL business as they readied a fighting stance.

(Deos' Apartment)

Dr. Alphys was suffering a nose bleed from what she was watching via her hidden cameras, Cali was sounding annoyed at the lack of information.

"What is it, Alphys?!"

"Deos has r-received a massive anime power-up and he looks p***** and Undyne...looks like she's having fun." Said Dr. Alphys, the affection in her voice after she said "Undyne" was obvious.

"WHAT?! How can you be turned on by that, they're going to kill each other!" Cali said angrily.

"S-Sorry, I got a little c-carried away, anime and Undyne...don't worry about Deos, we know t-that he wouldn't try to kill her, it's Undyne trying to k-kill him that's more the problem." Dr. Alphys said.

Cali sighed "You're right, let's hope neither cause too much damage to the other."

"You know, he looks kinda cute..." Dr. Alphys said playfully.

This makes Cali gasp "Alphys!"

"I'm just messin' with ya, I'm already taken...well, I-I will be..." Dr. Alphys said with a smile on her face.

"Okay, just tell me how the battle is going." Cali said, relieved that her reptilian otaku insider wasn't serious about being attracted to Deos, she wasn't as close to him as Dr. Alphys was to Undyne...but that doesn't mean that they can't be.

How will the fight between Deos the Determined and Undyne go? How will they make any progress through Waterfall and how will Cali and Dr. Alphys react to the aftermath? Find out in Chapter 13: Determined Roast