BLUE TONGUE SKINKS

I've had my Halmahera bts for about 5 months and got him as a baby. He doesn't run away when I hold him or show any signs of terror or hiss, but he huffs a lot when I handle him and runs from me when he's in his enclosure. He also doesn't bask much or come out of hiding until I leave the room. I've tried everything with feeding him and handling him often but he still behaves like this. Is this just typical "teen angst" / young skink behavior, or is it just a part of his personality that won't change?

I wouldn’t be too worried. He’s still pretty young so he is probably still just getting used to you and getting used to being handled. In my experience handling blueys, both my own pets and ones i’ve found in the wild (i live in australia and enjoy herping), puffing up and huffing aren’t a huge concern. If he’s squirming aggressively, biting, or baring his tongue, i would leave him alone and not attempt to handle as that is a clear sign he is very uncomfortable/afraid. But if he’s just huffing a bit and doesn’t seem uncomfortable or stressed out while being handled, that’s very normal and most likely just means he just needs to get used to it. For me, semi-frequent handling for short periods of time, and more ‘hands off’ handling where he has some space to free roam but also interact with you (ie, in a play pen or lizard safe room) is probably the best way to let him slowly adjust to you. It may also be his personality though; plenty of lizards are just a bit grumpier than others.
My bluey, Jaffa, used to huff at me a lot as well, and used to always hide from me and now she no longer hides from me but still hides from just about everyone else. she loves being handled and having play time together but used to kick up a big fuss about being taken out of her enclosure.
Give it some time, build up some trust with him, and don’t worry too much.

I couldn't agree more with the last response! Completely normal behavior