My muse is dragging his feet here.
All I have is a light haired nerd who floats around sometimes when he walks. Is that even a thing in the potter-verse? Spontaneous loss a gravity?
*stares an pen and empty piece of paper*
How about this:
(Just jawing to help that muse pick his feet up)
He's a huge quodpot fan so he has a pair of mercury shoes he wears sometimes, unfortunately his shoes apparently have a mind of their own (much like Hagrid's favorite teaching texts), and they get a wild hair up their backside and decide to make him float every now and then when he's not paying attention (tricksy things they are).
Or how over the summer, his cousin (or sibling or someone who is magically inclined) put a charm on them, as a prank, but he doesn't know how to get them uncharmed and neither does said family member who did so.
What sort of activities does he enjoy? Taking care of magical creatures? Dragon lore studying? Civic duty? Chess? Choir?
Have you considered a song for him yet? That might help wake up your muse a little bit.
Just throwing out some ideas for ya :)