This one is an alpha/alpha omegaverse Johnlock:
Passing for Omega – So they can infiltrate a club for a case, Sherlock must pretend to be an omega. Plans always come with unexpected complications.
teaser below the cut
“I can hardly believe you’ve talked me into this,” said John, for the fifth time that afternoon.
“It’s working perfectly fine,” said Sherlock evenly, ducking his head as someone else turned towards them.
John growled at the stranger and the person quickly hurried on. “You just had to pick up the omega heat pheromones, didn’t you?”
“I told you, the containers were not clearly labeled. The black market isn’t known for the most meticulous handwriting. We’re almost there.”
“Oh yes, this is brilliant. Taking you, smelling of heat, into a club packed full of alphas.” John held Sherlock’s arm a little tighter.
“They’re all bonded, that, after all, is the reason I am doing this. They would never allow two unbonded alphas anywhere near the place. And frankly, you could never pass as an omega.”
“Thanks, I think. This is it, yeah?” John looked up at the non-descript building. He could smell omega from here, but mostly Sherlock being damned distracting.
Sherlock handed him the necessary credentials and John marched up to the door, Sherlock close on his heels. The guard looked them over. “He’s in heat.”
“Just barely. I can handle him. Or anyone else.” John bared his teeth. At least being protective didn’t require any acting.