I want an AU where Steve is a werewolf and Eddie is a vampire except neither of them know about the other.
Eddie is the frontman of an up and coming band, but he's left his coven and surrounded himself with humans. They perform after sunset anyway so it's easy enough for him to hide his nature.
Steve has similarly left his toxic family pack and built his own pseudo-pack through the kids. He works as a park ranger. Or an ornithologist. Or something else nature-y/nerdy. But no one knows about his furry little secret.
Maybe Steve ends up attending a concert with one of the kids who has VIP passes and Eddie zeros in on Steve immediately at the meet and greet because he's pretty and preppy and delightfully out of place and also he smells good.
And Steve is having similar thoughts, but he tries to play it off because there's no way an honest to god rock star would be interested in him and his polo and his boat shoes (also his hearing is temporarily fucked from the concert, so he doesn't register Eddie's lack of heartbeat).
After some light flirting, Eddie invites Steve back to his hotel and Steve is like, you know what? Yes. I am going to have a one night stand with the gorgeous front man of a metal band and I'll probably fall a little in love with him by the end of the night and it will break my heart when he kicks me out in the morning, but it will be an experience. Let me go drop off my kids and I'll be right back.
Except what he doesn't know is Eddie is planning to have a little snack while they're in the throes of passion––not enough to hurt Steve or anything, just enough that he'll have a pleasurable blackout and wake up tired but sated.
The only problem is that neck-biting (that breaks the skin) for wolves is the equivalent of marriage.
So when Eddie bites Steve, instead of a venom-drunk human, peacefully slipping into sleep in his arms, he gets a very horny, very confused, werewolf who is now insisting that they're married.
I can't decide if it would be funnier if Wolves/Vampires didn't know about each other, Ie:
"You're a Werewolf?" Eddie says, "What do you mean you're a werewolf? Werewolves exist? No. Shut up. Prove it."
"Holy shit. A vampire. Vampires are real," Steve reaches for Eddie's face and Eddie is so baffled by the everything of this situation that he lets Steve pinch Eddie's top lip and peel it up off his fangs for a mortifyingly long moment. Eddie draws the line when he starts poking at Eddie's incisors, though.
"Why do I feel funny?" Steve mutters. "Will your venom kill me?"
"How should I know," Eddie hisses, only a little hysterical, "I didn't know wolves existed until two minutes ago, I've never bitten a wolf before."
"And you won't be biting any others, mister. Infidelity is not ok."
The other option is that wolves and vamps DO know about each other but stay so isolated in their covens and packs (and loners are super unusual) that they never interact. So Steve and Eddie are both like, dang, I'd been raised to think all of your kind were smelly/ugly/gross, but you uh, don't fit into that box at all. Weird.
Regardless, Steve (still naked, probably) crosses his arms all huffy, like, "well, we're married now, you're not going to bite me and then cast me aside like some harlot," and Eddie is like "...I'm weirdly ok with this, actually. No arguments here." And eventually they live happily ever after.
