Note: It's a headcanon of mine that The Marauders + Lily never ever mentioned Remus's furry little problem around Harry when he was a baby so he wouldn't understand why sometimes Unca Mooey got sick and couldn't turn into an animal like his Papa and Unca Pafoo.
I don't own HP.
Sometimes, outside, Papa turned into a great big Bambi. Well, Mama called it a Bambi, Papa called it a Buck. But it had great big pointy things on its head and soft fur and he let Harry ride on him. He rode on Unca Pafoo too, but it wasn't as fun as Papa's rides.
Unca Peer turned into a mouse and Harry was too big to ride him, but he had a fuzzy tail that gave Mama the 'heebie-jeebies'. Unca Mooey didn't turn into anything. But he did give Harry piggyback rides and rides on his shoulders to touch the ceiling.
Harry wanted to turn into something too! He wanted to play Bambi and Doggie and Mousy with Papa and Unca Pafoo and Unca Peer, but he couldn't because he couldn't turn into an animal just like Unca Mooey and Mama.
He asked Mama one day if she could, but she just laughed and said only gross boys did that. Harry wasn't a gross boy, he was a good boy, Mama said that when she tickled his tummy and blew raspberries.
Maybe if he got dirty he could turn into an animal? He would have to get Unca Mooey dirty too somehow.