Mason works as an assistant at the Curtises' butcher shop and is known for being more direct and outspoken than his boss Sig. He's been part of the operation for years—at least since the Elric brothers first showed up as Izumi's apprentices.
Fans often note his role in one of Izumi's toughest lessons: that month-long survival challenge on Yock Island where Ed and Al had to make it without using alchemy and figure out what "All is one, one is all" actually meant. The "monster" that kept hunting them down? That was Mason, acting on Izumi's orders. She had him keep watch over the brothers in disguise to make sure they didn't actually die out there—which, given how brutal the training was, probably mattered more than the boys realized at the time.
Content compiled by AnimeList.moe from publicly available sources.
