haha I just left him alone... If anything It'd probably have been him with Aiden. 
as far as I can see the hardest to kill in their sleep would be Aiden and Mina. 
Mina has training (I think...)
Aiden has his father's boot camp coupled with his animal instinct and self taught skills.
Eira has the same, but I don't know where Kitty is... 
Actually... I think everyone is here except her and Mina...
KITTY! MINA! WHERE ARE YOU?!?!?!?!