Board Thread:General Discussion/@comment-31252171-20171008174544/@comment-32182236-20171013140031

The theme for Determination is actually "Don't Give up", which uses the "Ruins" letmotif. This is the theme that plays when you're so determined that you refuse to die, and survive with a fraction of 1HP. Undyne uses that letmotif because she's ALSO determined, though to strike you down.

Spear of Justice is another one of the letmotifs that is split into several sub-letmotifs. Don't Give up is the same as the second letmotif in "Spear of Justice"-The first being a variation of "Undyne", and the third being completely original.

Though, "Don't Give Up" could also be Frisk's theme song...