You love to watch the MTT channel with Papyrus towards the end of the day. He has became both of your celebrity crushes and you both promised that if one of you got to date him, the other person wouldn't interfere with the relationship in any way.
That promise gets hard to keep once you find out Papyrus has actually been friends with Mettaton for a few years now.
This is going to be a slowburn-ish type story. Undertale and all it's characters belong to the brilliant Toby Fox