#billy batkid

I haven't been into Billy fanfiction for very long, but I'm looking for something similar to this idea. (Because I can't get it out of my head and I'm too lazy to write it right now.)

Make Billy older than he is in canon. I mean, he's still biologically 10 years old, but chronologically much older., But spending so much time as Captain Marvel prevents his body from growing because he's almost never in it, being a street kid and all that.

And if he's still friends with Freddy, it's technically recent if we consider that Billy would be over 100 years old. Billy only just begins to notice all these strange things, like the fact that the time he's been alive is actually much longer than the 10 years he thinks and that their perception of time is simply ruined by magic, But he stops being Captain Marvel for a while while he is being adopted by the Batfamily without anyone knowing that he is Captain Marvel.