uselessundertalefacts:

hmmmm

Ok I do want to elaborate on this actually.

The interesting thing about what Ralsei says here is it reminds me of one of the library books in Snowdin:

Monster SOULs are made of “love, hope and compassion”, but monsters don’t know if human SOULs are the same. If we assume the red soul is human, maybe this means that human SOULs are made of “will, fate and compassion”.

The other interesting thing is that Ralsei doesn’t mention determination. In fact, the word “determination” isn’t anywhere in Deltarune. But he does mention “WILL” and “FATE”, which sound a lot like Alphys’s description of determination.

The thing about determination in Undertale is that it’s a really complex concept that has a lot of different meanings depending on context (really it deserves its own post), but you can distill it into two big ideas: the “will to keep living” (aka the desire to complete the game, the power to come back after dying) and the “resolve to change fate” (aka the desire to get a specific ending, the power to reload/reset at will). Both of these ideas are called “determination” depending on the context.

So what if the physical substance that Alphys calls “determination” actually has two components: “will” and “fate”? The amalgamates (and maybe Undyne the Undying?) could have the power of “will” to keep themselves alive, but not the power of “fate” that Frisk and Flowey use when they use save files.

This could also explain why the word “determination” is never used in Deltarune even though Kris has a human soul and a save file. It’s not that the concept doesn’t exist here, it just has a different name (or two names). And the concept of “will” does come back later in the game, during the King fight!

King mentions “the Knight’s will”, which could just be the way he talks and not a reference to “will” as a special magic thing. But the narrator also uses the word when you get the three special ACT commands. And since those commands involve the red soul shining its power on Susie and Ralsei to enhance their spells, maybe this is the “will” Ralsei mentioned during the tutorial.

And to tie this back to “determination”, these two lines sound a lot like “the will to keep living”, don’t they?