Ye Yu

After leaving Linde's soul space, Undyne returned to her original form, a complicated expression on her face. "Asgore... he... so that's how he felt..."

"..."

"Honestly, I... I think I can understand how he feels..." Undyne lowered her spear and looked up at the patch of Echo Flowers nearby.

Undyne was violent, not stupid. She could figure out plenty of things pretty quickly.

Hadn't she, too, shouldered the hopes of so many monsters?

She had her own hobbies and another side to her, but to give the monsters a sense of security, she could only put down her comic books, set aside her piano scores, and show them her strongest, most unyielding side.

Though she did rather enjoy doing it.

Still, that was precisely what allowed the monsters to live with peace of mind and confidently tell others, "With Undyne protecting me, I don't have to worry about being in danger!"

That would wear her down eventually. Even if her passion and perseverance kept her going, she couldn't bear everything alone. That was exactly why she needed her comrades in the Royal Guard.

She looked straight into Linde's deep eyes. "All right, human. For now, I'll recognize your right to be in the monster kingdom."

Linde nodded solemnly. "Thank you... Oh, and Undyne, be careful with that power inside you. I really can't guarantee that magical beings can keep determination under control."

"Huh? That power... was your doing?" Undyne couldn't help being curious. After all, Alphys's "history books" were rather one-sided and didn't do a very good job of documenting humanity's various wondrous abilities.

"No... Alphys should know... That power inside you is called determination," Linde explained. "And your body produced it on its own."

"Alphys... she knows about it..."

Elsewhere, Alphys's emotions were all over the place.

She had watched helplessly as the monster she loved developed determination over a misunderstanding, only to see Sans, Gaster, and even the flower she had created appear one after another and ultimately save Undyne.

She felt incredibly relieved. At the same time, her researcher's soul began stirring, clamoring to figure out what was in Linde's vial, because it might very well save the Amalgamates in the True Lab!

But when she saw Linde inject the entire vial into Undyne, she nearly fainted. Such precious research material! Gaster gave it to you himself! And you just used it all up! Fine, he was saving Undyne, after all. I'll let it slide!

Alphys remembered when Sans had led Linde to the True Lab to collect determination. He had promised that he would save the Amalgamates, and the earnest look on his face... Fine. I'll trust you!

And so Alphys stopped dwelling on it.

Meanwhile, elsewhere.

In a certain space, a consciousness grew increasingly furious. It discovered that the thing invading this universe was secretly being protected by that dog! It couldn't kick him out of this universe!

Then... there's only one way... Erase this universe... and then restart it...

So, who should I have erase all of this? First, I'll find a vessel. With that thought, it turned its gaze toward the invader's home, to a planet called Blue Star in that universe...

Having someone from your own world destroy you... ought to be quite entertaining, wouldn't it?

Linde and Frisk were visiting Undyne's house when Linde suddenly sensed intense malice and murderous intent directed at him.

"It's that entity. It should be starting to prepare its move against you."

Toby the Little Dog's warning rang out in Linde's mind.

"Roughly how much time do I have left?" Linde asked quietly.

"I can hold it off for a little while longer, about ten days... After that... it'll all be up to you."

A powerful sense of urgency rose within Linde. It looked like he would have to work hard at practicing magic...

On Blue Star, Ye Yu was walking down a street when a runaway dump truck suddenly barreled toward him.

Ye Yu couldn't dodge in time and died on the spot.

"A human blessed with good fortune... Interesting... Choosing you was indeed the right decision..."

Ye Yu's consciousness was stuffed into a black-and-white body the entity had casually fashioned.

A soul... There's no need for a soul... All he needs to do is kill... There's no need for a soul to sustain emotions...

Determination... He needs more! More!

In a stretch of void, Ye Yu opened his eyes. His emotionless crimson eyes reflected his black-and-white body as he looked at the ball of light floating before him.

"You are...?"

P.S. The first real boss is about to appear! Though he won't descend into the world right away.

Ye Yu is a pitiful pawn. He was an ordinary person in his original world, but he will soon lose every shred of his humanity. As the author, I haven't actually decided whether to kill him off or save him. Feel free to leave your thoughts in the comments, since he was originally innocent...

But I can share a spoiler image. See the author's notes section.