This is why flash drives exist. Always back up your back up.

Okay I have to ask, did he steal it and wipe it JUST to be an asshole, or was he using it for something else? Whole different level of malevolence here, and I want to determine if he should just get his ass kicked, or if a firing squad is more appropriate.

This is why backups are important.

Flash drive, email it to yourself. google drive. Look at a printed copy. Lots of ways to recover it. I hate to rewrite an entire 25 page essay when my original got corrupted but I had a printed copy with my edits on it. Or your brother will be spending the time and allowance trying to recover the drive with a drive recovery program.

You should probably start typing that.

How thoroughly did he wipe it? You might be able to recover the file. Check out e.g. The Sleuth Kit: https://www.sleuthkit.org/sleuthkit/desc.php

10 pages is nothing though, I'm sure you can quickly type it again??

It really surprises me that people nowadays stil run into this problem. Always make 3 backups, one on your pc that you type it on, on your phone and one online. In this case you will always have acces to your files no matter what happens.

I call b.s

you're supposed to save that on two differend harddrives and a cloud...