(For a 17 year old character)
[name_f]Atty[/name_f] is lovely, but I’m not sure how well it works for an older boy, id love some suggestions!
[name_u]Kit[/name_u], and maybe [name_u]Fox[/name_u] (if kit is a nickname, fox could work…)
At, [name_m]Ti[/name_m], or a nickname not related to the name but to the personality/experiences of the character
Perhaps [name_u]Gus[/name_u], or a nickname related to the character’s appearance or surname.
[name_f]Atty[/name_f] is great! What about [name_m]Tito[/name_m] or Athos?