[ And yet. He dips his head lightly as if in apology before drawing back up with an easy, but much cooler smile. ]

So, please, do not take it personally. Your kindness is simply quite misplaced.

[ Sebastian looks back to Kaeya and gives a light nod that makes it clear that he's agreeing to the terms. He'd hold out his hand to take the vial, but considering the tension here, he feels that it might be unwise. His attention at least turns back to Ryunosuke, since by his own personal standards, he feels the good manners are at least worthy of being rewarded with an explanation, at least in part. ]

I would prefer it have been done properly, since skipping out on a bill is quite rude... But only shadow and darkness could ever call to me. If it asks me to be its slave and serve a despot, well.

[ He shrugs almost lazily, far too casually for what he's admitting. ]

It would not be the first time, to put it plainly.