fractious

frac·tious
ˈfrakSHəs
ADJECTIVE
(typically of children) irritable and quarrelsome:
"they fight and squabble like fractious children"
SIMILAR:
grumpy
grouchy
crotchety

(of a group or organization) difficult to control; unruly:
"the notoriously fractious resistance groups are declaring alliances to bolster their collective power"

She found her brother’s fractious behavior annoying.