So, headcanon time- Gates is Avery. He’s just about the right age, and history tells us that Avery was shortish, stoutish, and had a “merry complexion” and a sort of dangerous air about him. Oh, also Gates’ first name is Hal, which is short for Henry, and he wanted Avery’s journals but doesn’t seem to have needed to read them. Can we say “they’re actually his and he didn’t want anyone else recognizing that handwriting”?