I really like your theory about Spamton basically haunting a mannequin after death. Have you ever touched upon the reaction from Jevil (or anyone, really) upon seeing the new Spamton? Especially considering Spamton isn't even aware he 'died'.

^ how i think jevil's first sight of Spamton would go. i love this ask. this is referring to some headcanons I made a while back, I'll link it here for the one post and the general ghost spamton theory is linked in that one as well. Going to elaborate on it more under the cut for those interested + more art.

In general I think that people from Spamton's past wouldn't really care if they notice at all, since he wasn't in the business of making close friends with anyone. With the Addisons, in my interpretation he had a "weird co-worker" relationship with them, and while Addisons in general treated each other like potential business competitors that they had to make-nice with, Spamton is especially easy to single out for being visibly and temperamentally different. His altered, current state is something they'd feel at least uncomfortable by, but many wouldn't have been too close with him to begin with for them to talk about it with him directly. Would get whispered about between each other for sure, like we saw with them talking about Spamton after the NEO fight. It moves him from the "disgraced guy I used to know" category to the "actually unpleasant to look at or think about" territory. This goes for Swatch, Queen, and Seam (less so), who seem to buy heavily into the Lightner and Darkner dynamic, with Spamton corrupting the Lightner's dream being a strong taboo against what it means to be a Darkner.

As for what Jevil thinks, Spamton during the NEO fight is both a beautiful and horrifying display. Jevil at this point hasn't seen him in years since his imprisonment, and in their time apart Jevil has grown to find novelty in the cage that everyone else besides him is in since he's created huge emotional distance between him and the reality he lives in. Seeing the fact that Spamton had corrupted an abandoned dream of a Lightner and was causing so much chaos to the established order of the world would be exhilarating, but at the same time seeing that Spamton had accomplished this and still had his strings visible (and changed to a marionette puppet with no symbolic agency), it'd be a painful confirmation of his worldview that even Spamton, who deep down he still cares for, could never have been free.

Jevil would think at first he'd just gone through some nebulous situation to change what he looks like, since ofc he himself has toy-like traits (arguable if that happened with Gasterfication or not), Seam is a plushie cat, and other Card Castle Darkners are based on toys, but feeling the lack of life combined with the symbolic body of Spamton would mean to him something bigger had went wrong. He wouldn't dare to bring it up in an empathetic way, stuck in his mindset that it doesn't matter, but it'd still hit a part of him he doesn't like to think still exists. It's something he gets over quickly, almost performatively going back to fucking with him and taking advantage of his fear for entertainment, but it didn't sit well at first.

To me, the fact Spamton "died" isn't really a huge deal, kind of like with the ghosts in Undertale where no one really cares they're just ghosts. They're just doing their thing. To me it'd be fine if neither of them find out what happened for certain, but it's something that adds Flavor to his character.