Board Thread:General Discussion/@comment-31252171-20171008174544/@comment-32182236-20180218164139

Hopes and Dreams actually IS a theme of Asriel. It contains “Your Best Friend (CLEARLY a Flowey theme), “Once Upon a Time” (Chara’s theme), and the Snowdin Town theme.

Now, Sans’ fight is similar to Undying and NEO here, but it’s not the “hero”song that’s being played. The “hero” song is the theme of Battle Against a True Hero and Power of NEO (They both share the same lietmotif) Megalovania doesn’t share that lietmotif at all.

What do you mean “traditionally the theme of the power-mad final boss”? We don’t hear this song anywhere else in the game. Closest you’ll get is what might sound like Megalovania in Bring It In, Guys, during Sans’ and Papyrus’ section. If we count this, that actually counts as further evidence of it being Sans’ theme. Other than that, Megalovania has no other appearances. If you meant Earthbound’s Halloween Hack, well.. That’s a completely different game, and that’s ONE appearance. (Homestuck’s a webcomic, not a game, so that doesn’t count.)

Characters can have more than one theme-Heartache is a completely separate song from Fallen Down, for example. Mettaton does as well-Death By Glamour (which combines “It’s Showtime” with the “Reporting Live” themes), and “Oh My Love”. They’re BOTH Mettaton themselves.

Therefore, Megalovania being Sans’ theme is the most logical. I mean, when you battle someone, it’s always THEIR theme that plays, never your own. Why wouldn’t the same be the case for Sans? (And before you say “But Sans attacks first!” Well.. So does Undyne, actually, by turning you green.)