“Why would you do that for a man you don’t know?” Bucky asks.
Steve raises one slow eyebrow at him, then the other, till his expression turns from skepticism to disbelief. His forefinger and thumb reach into his shirt’s front pocket and draw out a wrinkled dollar bill.
Steve looks him in the eye when he says, very patiently, “For money, Bucky.”
Source: you go to my head – Chapter 1, by alby_mangroves, brideofquiet – Captain America (Movies) [Archive of Our Own] | https://archiveofourown.org/
Awesome pre-canon fic. Locked for AO3 users.