So Sasha is more cruelty than Lilla... the weirdness and craziness of these twin sisters reminded me of Satanophany's Dojima twin sisters (Seri and Maki)...
Daiankokuten might be partly right. I don't think Sasha is necessarily more cruel though, just more inured to it. Leila might become more cruel in response to people that she perceives as cruel.