I come bearing fic, thanks to The PolyA Exchange:

Title: stake a claim
Author: inkvoices
Length: 5713 words
Characters/Pairings: Clint/Natasha/Bucky, implied past Clint/Natasha and current Natasha & Bucky
Rating/Warnings/Other Tags: Explicit (vampires, biting, prostitution but selling blood, mild bondage, mild dom/sub, knife play without blood, scarification with teeth, shaving) (also: consent, trust, scents, vampires don't have a sex drive, and trans Clint Barton)
Summary: The man stupid enough to come between James and his prey is, annoyingly, a head taller than him. There are no obvious bite or mark scars on his bare arms, although he has an underlying claim smell, faded to stale air and grave dirt.
“Hi,” he says, with a smile that James would swear is genuine as much as he seriously doubts it. “I’m Clint.”
He pauses, clearly waiting for James to respond, but James is too busy trying to work out what the hell this guy is thinking without letting the incredulity show on his face.