He lost his parents young and grew up in an orphanage, which seems to have left him with a wandering streak. After leaving the orphanage as a kid, he spent years drifting around before eventually settling down—these days he's focused on being a solid father figure to his family, though that restless nature probably never fully goes away.
The black top hat is basically his signature. He's got "M.P. from your M.M." painted inside it, which he says is to make sure his hat doesn't get mixed up with anyone else's (though let's be honest, how many top hats does one orphanage have?). He takes the thing seriously enough that it's almost always on his head.
He also spent some time living on a ship with three Hattifatteners, which he apparently found fascinating enough to observe them closely. That kind of curiosity—just settling in somewhere unusual to watch how things work—tracks with the whole drifter backstory.
Content compiled by AnimeList.moe from publicly available sources.
