You don't have to do anything. It's not your problem in the least. Just... welcome your friend. Do something fun together. You can surely find a way to survive having a little breathing room for a while, can't you?

[Just. Breathing room. Sounds nice, doesn't it? They sort of debate leaving their hiding spot, getting up, just pointing that restless energy into harmless wandering. Nowhere to really go, though, is there? Asriel's outside. Frisk's probably scouring the halls.]

Live your life for a bit, right? Be happy. Show Asriel the closets. Tell him he can ask for a video camera. He used to like having a record of happy memories. Show him real stars. Show him a happier sunset than I ever showed him. Let him try human food out. You should be excited. Look at all the possibilities you have now.