A girl would be great. She hopefully wouldn't have to go through the same training and have to perform the same tasks for the royal family. I don't think Roselia would be okay if she knew her child was receiving that training.
I hope too but I also hope that he won't do anything bad to her sister just because of jealousy(⌒▽⌒) Neeliv
Maybe that won't happened because "IF" they have a daughter and have a same beauty of Roselia, Ain would thought that he will protect his sister at all cost. Woooo.. .. imagination from the fan here hahaha ε=ε=(ノ≧∇≦)ノ
Arghhh I hope Cassius and Roselia will have a daughter though, so that Ain will protect his adorable little sister. ε=ε=(ノ≧∇≦)ノ