He saw you swimming in the depths of Atlantis, the sea of Poseidon. You were a mershark, those species were rare in this age. They were captured as to show off that they have a rare species among them. But, you was a purple one. The top of your hair was white and faded to a purple at the bottom, with blacked out eyes, shark teeth and webbed hands. You looked lost, he got the idea of trying to capture you.