For those who don't know, a few days ago Toby posted several snippets of dialogue from Deltarune Chapter 5 on his Twitter, and these included the start of a conversation with Seam about the Shadow Crystals. https://x.com/tobyfox/status/2006883392516927960
So I've been thinking about the Shadow Crystals probably being vessels for Determination in Deltarune and Determination in general. I haven't been into UTDR for very long so most of my knowledge on Determination comes from Mollystars' Device Theory/analysis series, which brings up that Determination works demonstrably differently from its behaviour in Deltarune, one reason being that the player has three save slots but obviously not three souls.
Determination in UT grants the ability to create save states to literally de-terminate, to go back to before one dies or to halt death for the Amalgamates. Determination in Deltarune, however, is possessed by both human and monster Lightners, all Lightners in fact, and while it's possible Kris's Determination has a hand in allowing them to revive, they don't have total power over their save files whereas the player or Soul and Gaster do, which leads me personally to believe that saving is not necessarily a power of Determination.
We know that all Lightners possess "this power of Determination", implying Darkners don't, and that Darkners can be driven mad upon attempting to use a small amount of it. So what is Determination? I feel that Determination is the power of control over one's own actions, life, or narrative, the power to determine... well, anything (This may have also been present in Undertale as Flowey and the player were able to determine the ending of the game because of their power to reset, again idk very much about that, sorry).
Since ch4 I've largely been looking at DR as a world where agency truly cannot exist because it's fictional, the actions of every single character are quite literally determined by a script, and the prophecy is a representation of the plotline that the game will follow no matter what, so under this lens, how does it make sense that any character can have Determination? The answer lies in the mechanics of a Dark World's creation by the hand of a Lightner. Everything about a Dark World is determined by the Lightner that created it, although probably subconsciously. The world and its inhabitants are based on the Lightner's experience and memories relating to the space the Fountain was created in, thus the majority of the aspects of a Darkner's life are determined by Lightners, and that is why they are perceived as having Determination by Queen.
Perhaps when a Darkner uses a Shadow Crystal, it allows them to see the power of Determination, but not truly use it. Jevil realized that no matter what he did, he could not change the course of events and he had no tangible impact on his own existence. He may have found this revelation "freeing" since it meant he could do whatever he wanted, but he was shunned for his behaviour and became isolated in his knowledge of the world. An intrinsic part of Spamton's character was that he was "unlucky" as an Addison, no matter how hard he worked he could not become successful on his own. It wasn't until he got help from a mysterious entity that his work could have any effect on his status in life, he may have been determined, but he lacked the power to determine his own fate. For his entire existence his failures and successes are determined for him, he literally could never have gotten Neo on his own because his failure was guaranteed by the powers that be, he needs someone with the power to create change in the world to decide to help him.
Gerson is a mysterious case. He was a Lightner possessing Determination in life, and he chose not to use the Shadow Crystal. Is this because he already understood Determination and his relationship with reality, or because he still had it? Going by the logic that a typical Darkner cannot independently act in ways that will affect the story and he very much can, I would say that he must in fact still have Determination, however the mechanics of all of this is still not set in stone so at this moment we can't really know for sure.
I don't really know much else in regards to this particular theory, like what the Knight having a Shadow Crystal implies, why they wanted Gerson to use one, what the flavour text for using them in the Light World has to do with Determination at all, how exactly Ralsei works (he closed the Great Door in ch1, does this mean he has some amount of Determination, or does that not count as affecting events? My head hurts). It does draw one last thing to my mind though...
Ever since I learned about Friend's heavy association with RNG/chance/luck, I've sort of assumed that they're an entity with power over it, and (also making a pretty big assumption that they're Spamton's benefactor) that they literally changed Spamton's luck value, or odds of success, in order to let him become a big shot, then set it back to zero after the last phone call. It's only now though that I realize how important random chance might be in a world where so many events are predetermined. There is a tangible relationship between luck and fate. I wonder what it could mean...
(Please don't take any of my interpretations as attacks and try to fight me over them, I'm just having fun speculating out here! Be kind to your fellow fans 🙏)
