Genuinely one of the best and most original things I have read in recent memory. Admittedly, the cutesy art style made me a little skeptical going into things, but your storytelling has an emotional maturity to it that I didn't expect. Plus I've never seen a character quite like Mary in any medium before, visual novels or otherwise.
Crowven's route was probably my favorite one in terms of story, just for how well it deals with the subject of grief. But Reginald hits all my niche interests in a character, so I'd say he's my favorite part of the game overall. I will say that I think he could've been worked into the main plotline better, and that both of his endings feel pretty abrupt; he almost gets a stronger send-off in Twyla's good ending than in his own route. (Disclaimer: I'm not sure if my true end save file branched off of Crowven's route or Reggie's, so maybe I missed a couple of Reggie scenes that would explain the mysteries around him better? He only appeared once in that playthrough.) Regardless, if you ever made a follow-up game with him, I honestly would love to hear more of his story.