Curate, connect, and discover
You're like holding burning coals
Olrox: I'm not in love with you
Olrox: I don't want you to die
DENIAL IS A RIVER IN EGYPT MY DUDE
There's a lot of reasons I'm not on board with the Alucard/Maria ship (in Nocturne's context, I still have yet to play Symphony of the Night and so can't speak to their game counterparts) but one of the reasons is that I genuinely think it would be the most boring route to take that would also be the biggest disservice to their characters.
Maria is clearly unmoored right now; she's lost her mother, she's killed her father, and Richter and Annette have left. She only has Juste and Alucard, both who she only just met and has no real strong attachment to. She's throwing herself headfirst into a revolution that's about to turn incredibly bloodthirsty, echoing her own descent into violence and vengeance.
She's likely developing a crush on Alucard, yes, but I think it runs deeper than that: I suspect she's going to latch onto him out of the belief that he's the only one who can understand what she's going through (vampiric parent, martyred mother, killed his father, etc.) And with Maria also turning increasingly towards vengeance and violence, I suspect this attachment is going to concern Alucard more than anything else. He spends decades trying to avoid human attachment, and when he decides to try again this child not only develops an unhealthy fixation on him, but also tries to use him as a blueprint for her own descent into vengeance. That's horrifying. That's juicy. That's going to give Alucard even more hangups about being in the lives of mortals. How can that not make him feel like a corrupting force?
"I want Alucard to jump on Maria as soon as she's 18" Well I want Maria to use Alucard to justify her wanting to behead people left and right while Alucard is wracked with guilt over having corrupted this child. I want them to make each other worse.