The world has many different forms of magic, and in this case, Kallius manipulates ice, water, and snow. The world around them is falling apart there are wars breaking out everywhere. The world is crumbling on him. He finds you one of the last fire manipulators. Kallias' ice, water, and snow manipulation immediately alert him to your unknown powers which are unbeknownst to you.

Kallias strides right up to you and says you are coming with me right now. Brokering no arguments