Logic suggests that Cassian has his own supplies, but it hadn't been an unthinking offer. Finnick owes his life to medical supplies delivered to him in the arena, provided by Mags and the sponsors who'd wanted to buy his beauty for the future with their support. He knows how valuable a commodity they were here, but he also knows that he and Annie have pooled their supplies, and for now, they have enough they can afford a small amount of generosity.

It's a small gesture, but it's important that he be able to make this small stand in the face of a man against whom he's been so completely incapable of any sort of self-assertion.

It's also a chance to recover. To get some soothing water and some distance between them for long enough to repair the walls Cassian is so good at breaking down. By the time he's made it back around the pool, Finnick's expression is as impassive as it had ever been. It's easier, with something practical to focus on.

When he makes it back to Cassian, Finnick unslings his pack and sets it on the ground, before he digs in it to pull out one of the little clear plastic cases he and Annie had split their most basic medical supplies into. Bandage. Dressing. Antiseptic. He doesn't have any of the near-magical medicine the Capitol sells to mentors, but it's far better than nothing.

Finnick tilts his chin towards Cassian's hand.

"Hold out your hand."