batter up!
― a baseball bat is her go-to weapon

beware the nice ones
― just because she's kind doesn't mean she won't kick your ass if she needs to

just a kid
― underestimated due to her age

babysitter friendship
― a special friendship between a child, and their caregiver

sibling team
― siblings working as equal partners

wise beyond their years
― a child who is smart and responsible for their age, in a positive way

innocence lost
― a child's innocence fades away as a result of a tragedy

young soldier
― a character having ot learn to fight to survive

cuddle bug
― sometimes all a character needs is a good cuddle

the zoomer
― a skateboard master

annoying younger sibling
― a younger sibling who's seen as (sometimes) annoying to their older one

definitions and tropes found on tvtropes.org (some definitions by me)