[Steve knows what he's really asking, that he thinks Steve wants something from him when all he really wants to give, especially to Bucky, especially when he so obviously needs it.]

You're right.

[He sighs dramatically, hanging his head before forcing his eyes up again.]

There is something. I was hoping you wouldn't figure it out, but... [There's a pregnant pause.] See, I might need something from the top shelf, and you're taller than me.

[He delivers it deadpan, but his eyes are overbright with mischief.]