Awhile ago I was re-watching some of the Fullmetal Alchemist: Brotherhood episodes in French (specifically 54) to reference something else, I noticed that in 54, Mustang uses the "tu" form (the informal "you") when talking to Hawkeye after being persuaded against finishing off Envy, which seems a bit odd. From the episodes/chapters I've read in French, they seem to usually use the "vous" form (the formal "you").
Does this correspond to anything in the Japanese original, and if so, what does it correspond to?
I've seen some other unexpected usages of "tu" elsewhere, but they weren't with characters that I've seen enough of in the French version to be able to see if it was unusual for people to use the "tu" form with them (in the context of the text).