All Levi has to do is voice it, and Erwin will make it happen. He'll dress up in a suit, make himself look immaculate and devastatingly handsome, and then take Levi apart to his base elements without getting a single wrinkle in his clothes or letting one hair fall out of place. That idea would actually sound pretty good to him, as well, so Levi should definitely bring it up.

Erwin glances up when Levi curses, but the hand squeeze and the flush he sees spreading across Levi reassures him. Seems like that was good, and something Levi would like more of. He knows Levi isn't looking at him right now, but Erwin smiles before squeezing Levi's hand back and ducking his head down again.

While this might be new for Levi, Erwin has, in the distant, ill-remembered past, sucked his fair share of dicks. He went through a phase in his cadet days, and then another one shortly after joining the Survey Corps, back when he could see all the things that could be improved to save lives but couldn't implement them yet. Part of Erwin forgetting and turning his mind off has always been orally focused, so this isn't just purely about Levi's pleasure. It mostly is, but Erwin is certainly getting something out of this too.

Using his free hand, Erwin loosely grips the base of Levi's cock, pointing it up into the air. With it like this, he's able to lick it again, trailing his tongue up over the shaft and then curling it around the head. He simply holds the head like that for a moment, tasting it, committing Levi's taste to memory, before unfurling his tongue and slowly, gently, dropping his mouth down around Levi's cock. He doesn't stop until his nose is pressed against Levi's groin, tickled by the fine dark hair there. Once he's got that done, Erwin folds his tongue around Levi's shaft and begins to slowly bob his head up and down.