Board Thread:Wiki Discussion/@comment-28440466-20160512075843/@comment-5956954-20160512080922

DarkAssasin999 wrote: It's just Mettaton, Invented by Alphys, That's Probably he just assumes it. undyne knows true plus OBVIOUS Why same-sex marriage? Alphys Female and Undyne? That's Lesbian. What's wrong with being lesbian?

Anyways, Mettaton is merely a suit for the ghost that once lived with Napstablook inside the pink house. You can find diary entries in there when you unlock the door with the Mystery Key. You will know the rest after some sleuthing.