"It's not preening, chickadee." He insists, fingers carding through his partner's feathery- no, not feathery. Not feathery because this isn't preening. Fingers carding through his partner's average normal hair.
You've teased him about this kind of thing before, and to be fair he does by definition preen his wings, you've seen it. After every mission, he sits down and begins painstakingly going and checking every feather for damage, plucking the unsalvageable ones, and then cleaning the rest. It didn't seem like anything to begrudge him as it was necessary maintenance.
But today you'd come back from your mission with leaves, dirt and other grimy paraphernalia collected in your down- no! Not your down. Collected in your hair, and he couldn't help but begin fussing over it, though you'd initially been insistent that you would deal with it when you showered that night, but you were busy at the moment and didn't think it was worth quarreling over.
That seemed to spark some indignant chord, which led him to eventually get you to relent. He'd spent a painstaking amount of time cleaning your tresses, which you assumed might've been the end of it. But no, afterwards he'd stuck by to give proper care while it dried and now he just sat fussing over perfecting how the strands laid. He'd been at it for nearly a half hour now but every mumbled statement that you're getting up is met with him saying he's almost done and then practically begging you to stay a bit longer.
He has you settled on his lap, his wings twitching as if he's instinctively preparing for his own pree- not preening. Cleaning of his own wings when he finishes with your hair.
He breaths in the scent of your shampoo, giving your hair one last run through before resting his chin on the crown of your head as he sighed as though this had been some greatly stressful affair and the cathartic relief had finally set in.