I write them into the story in a way that the reader knows that they are not as important as most of the other characters.
I think Max Ride and Redwall sold up to that age range.
She fights with Sebastian all the time.
Also, Diamondhead from Ben 10 was vulnerable to sound waves, which could shatter him, so your hero could be vulnerable to strong sonic and concussive attacks.
Also, have you decided on an origin story for the character?
Fortunately, I had saved a rough draft on my home computer two months before that.
And she says that in all seriousness.
For example, maybe he rises to power among the elves through his own actions rather than some accident of birth and lineage.