I’ve been playing in a game with my 11 year old nephew as the dm for the last few months and he’s like this. He’s great at the storytelling aspects of it but he gets pissed when we try to strategize before a fight and I somehow get critted at the beginning of every encounter… I ignore it because he’s a kid and I want to support him but I’d be lying if I said it wasn’t getting old.
Talk to him till he is still young and malleable. People sometimes transform into the worst and if that happens only thing I can do is walk away with regret I didn’t nudge them before
I talk to my brother about it and he’s working with him but I don’t feel comfortable being too hard on him myself. He doesn’t have a lot of interests and I don’t want to be the one that screws this one up for him.
One way you could maybe handle it is by discussing fudging roles in a way that isn’t directed at him. Just talk to the group out loud about the temptation to fudge rolls, but that it takes away from the fun of the game for everyone. He’ll hear it and likely understand, but it won’t be calling attention to him.