The change in Mat’s personality that many of us noticed in The Gathering Storm was deliberate. He’s reacting to being married, which was the last thing he thought would happen to him. RJ’s notes said specifically that “Mat refuses to become husbandly”, and he’s doing that by trying to go back to how he was in The Dragon Reborn . This is part of where the silliness with the backstories comes from—he knows that he was less serious and more of a joker at the time, but can’t really get back to how he was then.
When he was writing Talmanes, Maria mentioned that Talmanes doesn’t usually mock Mat in the earlier books. Brandon said that he has always read Talmanes that way, and that’s what he finds so funny about it—Mat doesn’t realize he’s being teased.
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