Not so much what he does, but didn't do. When I first got my betta, Napalm I got him a large cave to hide in. A dream for any betta right? Especially for one shy and newly bought by a strange ape.
Nope! He hid at the far back of his tank the first day and when he finally got used to me he still didn't use it until I tilted it to face the front of the tank. It's mouth has always been accessible, honestly I think it should be more difficult now tbh with the tank wall being two inches away from it. Whatever makes him happy I guess!