Thread:LaVey/@comment-1672596-20181222024858/@comment-3236835-20181222031936

Death's not given any storyline involvement in that game, nor in Castlevania/Super Castlevania IV, Simon's Quest, Dracula's Curse and Bloodlines, so there's really not much to say about it. I believe the manuals only limit themselves to say that he's "Dracula's confidant" and similar things (at least the English ones, I'm not aware if the Japanese manuals expand about his participation in those games).

Regarding ReBirth, there's a small "Trivia" bullet that mentions he was added to that game, even though he didn't appear in the original. If you wish to expand more about his participation in that (and/or the other) game(s), feel free to do it, jut please be careful not to add any fan speculation.