I decided that my interpretation of Morton still has the speech impediment, but it's not used as a joke. He's average in terms of intelligence, because I'm tired of every character with any sort of developmental disability either being really stupid or really smart.
I also gave him self esteem issues due to people making fun of his speech impediment, unsuccessful speech therapy (it kinda hurts him to try to speak "normally" because it takes a lot of effort), and seven siblings who have gotten into various amounts of trouble standing up for him.
Eventually he learns to accept himself. He's no longer ashamed of this part of him. He doesn't need to be fixed because he's not broken. And if others have a problem, their loss.
Also, he loves talking about geology. He won't shut up about it (/pos). If you have an hour to burn, why not listen to a teen boy ramble excitedly about rocks?
(yes, you can kill him with a baseball bat by showing him an obsidian knife. no, you shouldn't. yes, he licks the science. yes, he'd be confused if a world 8 rock was in world 3 until you revealed that it was a prank)
