Did you know that the track “Undertale” (yes, the title track, the one that plays when you first visit New Home) narratively reflects the story of Chara and Asriel’s relationship?
It’s true!
Toby Fox is just really really good at leitmotif, and even though dozens of people have written essays about the depth of Undertale’s soundtrack and integration with the story there are STILL new things to discover.
For instance, here’s underappreciated Undertale ost fact #84759836497238947: the opening of the track “Amalgam” is a distorted version of the “determined monsters” leitmotif present in “Battle Against a True Hero” and “Power of “NEO”“; skipping every other note and in a different key. I didn’t notice this until I listened to Yuuyu’s cover of Alphys’ theme from Underveil, which incorporates the lab tracks and in which this is immediately apparent.
But anyway, before I get too sidetracked: Analysis of what’s going on in Undertale-the-song depends on awareness of leitmotif, because Undertale-the-song is composed of two character themes: Asriel’s (Memory) and Chara’s (Once Upon a Time).
This is easiest to appreciate if you listen along, so either get out your copy of the ost or pull it up on Toby’s bandcamp page.