Gaster's Bunker

Welcome to Gaster's bunker! You can be anyone.
Gaster comes to Friend
Gaster: "So what's the problem?"
Friend: "Your stupid vessel doesn't want to get down from the tree!"
the vessel sits on a tree, clasping a branch
Gaster: "You just have the wrong approach."
Friend: "Wrong?! What do you mean?!"
Gaster: "Ahem," placing a mug of coffee on the newly formed hand , "Vessel..."
The friend chuckled.
Gaster: "Vessel, be a good girl and come down from there."
Friend: "Ha, that doesn't work..."
The friend doesn't have time to finish speaking, and the vessel falls right on him.
Vessel: "Okay, sir!"

Gaster's bunker is inhabited by several individuals. Gaster himself is a dark figure with a cracked skull where his head should be. He also has two floating arms with a hole in the middle. He can create more if needed.
Friend is a five-legged creature, similar to a cat, but much larger. He has a wide smile, one pink eye, and the other yellow.
The vessel is Gaster's attempt to create a human. Despite the fact that it's a failed experiment, he doesn't tell her this, as he doesn't want to upset her. She's about 16 years old, and because her personality isn't fully formed, she can't be upset, as it's unknown what will happen. Gaster's calculations even suggest it could create a black hole or a nuclear explosion.