Board Thread:General Discussion/@comment-31252171-20171008174544/@comment-32182236-20200204114337

Fallen Down is Toriel's theme, but Toriel's not the one that fell down, we were. So it refers to us, while being Toriel's theme.

Megalovania is Sans' theme, but that doesn't mean the name needs to refer to Sans. It can refer to us, and still be Sans' theme.