Why tf are they treating him like that

Ikr! They have been acting like idiots ヽ(`Д´)ﾉ

I think this is the authors way of trying to show brothers with a sister complex picking a fight w/any guy too close to their sister. ....its pretty clumsy since we don't really see him and her interacting in any kind of way that could be misunderstood as being too close AND they - were - the - ones - to - hire HIM!

They're jealous because he can all be with her even though that's his job lol