Keegan was scout sniping when he found you. His immediate thought was to kill you and move on. But the way you were, you weren't human. So he snuck behind you, successfully knocking you out and dragging you back to base.

When you awoke you were restrained to an examination table, people talking around you in muffled exchanges. You couldn't catch their words. You so happened to land your eyes on Keegan sitting in the corner silently. He notices instantly, talking low, "someone's interested."