I believe I already said this a while ago but I'm not sure...
Juste Belmont is the most beautiful Castlevania character. I wouldn't mind a night with him. He seems the romantic type, who lights a candle and presents you a blue rose (a type only exists in my mind so far).
That's a keeper.
For a one night stand, I think I wouldn't object a handsome mature man like Julius, or a wild encounter with Hector, or Trevor from the new canon.
Alucard seems like a man with whom I'd try some other stuff. He sure is romantic, but also cold and sad. I would read poetry with him, by the fire, while we watch snow fall through the window. Dreaming, always dreaming...
And last, but not least, I'm curious about trying a girl like Carmilla, or an intellectual like Charlotte.
Of course these are all fantasies...
But what would life be without them?
No matter what... the show must go on.