If True, Then Trite..

We are three i.e.two sisters and a brother...

My elder sister never gets into fight with my brother... But I and my brother are fighting fiercely... He is very childish.....Even when he is in class 10...We both get into a fight because of one or another reason... Like if something is mishappened by me... Then he blackmails me and says... Only if you will do so, then I'll think of not telling about this to papa... I'm acknowledging his demands... But still, he is a relative traitor... He let completed his all work by me and then tells everything to my dad... It irritates me. But when the turn is of mine... I'm also saying that only if...