User blog comment:Goregutz619/HXH episode 101 discussion/@comment-10851935-20131025094208

Anime productions are mostly supervised the author of the manga, so I think it is agreed between Togashi and Madhouse that the Chimera ants has blue blood.

Killua isn't mentally overpowered. It's how his mind works. He was an assassin who stained his hand with blood for crying out loud. If Killua is mentally overpowered, then same goes for Kurapika, Chrollo, and Netero.