It's entirely against Isa's personality to destroy GSS and his teammates with it. Isa's story, as I understand it, is a story of friendship and loyalty -- he meets Kachi, he is charmed by her, he sets out on a mission to protect her against the world. From what I've seen, he's both caring and thoughtful. Definitely not the kind to wipe out his friends just to score a win for himself.
Also, Isa and Selvaria have never been here before. Dunno what you're on.
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another place and time, without a great divide, and we could be flying deadly high