Being a teen!Avenger and Thor and Loki being like brothers to you would involve:
Thor is easy to bond with- he’s a great friend and takes you seriously as an Avenger -which the rest of the team sometimes have a hard time doing because you’re so young.
He has a habit of offering you (along with Peter Parker) Asgardian mead.
Loki, for the first time, interacts with you and tells his brother to stop being a moron.
[“They’re too young to drink Thor-”
“-Nonsense! You’d like some mead, right? Y/N?”
“Actually, I’m alright, thank you though.”
“Told you, brother.”]
After that Loki likes to ‘protect’ you from his idiot brother and despite the fact he doesn’t like to admit it, he actually enjoys spending time with you. He’s never had a younger sibling so it’s kind of… fun.
He teaches you magic. Mostly to help him mess with Thor.
Thor doesn’t mind the fact that his brother is trying to mess with him -after centuries of Loki playing tricks on him, he’s very much used to it- but he does enjoy that his brother is smiling more.
Training with you and trying to make you the strongest Avenger.
Fighting alongside each other in battle and being a force to be reckoned with.
The other Avengers are a little suspicious about Loki spending so much time with him but they don’t want to go against Thor- and they see how much nicer Loki has been since you’ve been spending time with the two of them.
Thor one day accidentally calling you sister.
He gets flustered but you assure him that you don’t mind because you think of him as family too.
Loki and Thor comforting you and trying to cheer you up whenever you get sad or depressed. They’re not exactly professions at this sort of thing but they do care about you.
Toad's Cave 