Uh............*Thinks deeply* 
Well for one he keeps hiding things from her. oh yea and when he died, everyone was on Arial's case and no one even bothered to see how she was going. 
also she feels that he doesn't show her the same love as he dose to the rest of the siblings. 
And he is related to Michel and was the reason she found out about her father, she regretted it as soon as she found out.
She hates the other siblings as well.