I went ahead and looked up some spoilers from the novel!
While they weren't the clearest, like we've already seen how different Ilya ia from the guide book's Ilya, yes he will be good <3 apparently the novel side stories are 19+ and someone had posted some mtl snippets on the forum and oh boy Ilya stays the same even when they get older, haha.
They also included a detailed snippet/description of the Bad Ending 1 and boy is it brutal, tragic, and sad it also seemed like Jerry experienced it as a nightmare at some point, so yikes.
Dang ghank
Damn thanks for the spoilers uwu, i love Ilya too so this is a win
Ilya pls don’t end up evil I love you too much. It’s not his fault he was shunned as a child!! </3