Then how would I do it? I'm acting just like I do around that age, and most of my RP characters are around that age, don't get why it doesn't work:blink:
I just edited it, but the part you posted also counts.
Maybe I'm acting way too Final Fantasy-ish ingame, but exactly what kind of trait woul make him looks more 15?
I think that large problem here is people automatically assume that you, the player, are 15. There's nothing wrong with that, but a 15 year-old with little RP or writing experience just may not RP an adult all that well and the general assumption is all pilots = age of majority. (I qualify this having read amazing stuff from 15 year olds and younger, just remember we are dealing with the expectations of the general internet).
I'd be able to say more based on what ID you have as well, some IDs sort of lend themselves to more mature characters.
Other than that, you could use unspoken hints where appropriate using *<stuff your character is doing>*. Might get the idea across and also allows your narrative writing to contrast the character's speech.