Kaidan is a Type L2 'biotic', which is hard to explain, but let's just call it psychic powers. His L2 implants are not up to the modern (L3) standard, and he suffers from heavy migraines. Unfortunately, he was assigned to the same team as Spongebob Squarepants, which is not helping his headaches.
As a member of the failed Thear expedition, Kaidan was on board the heroes' VTOL during the return to London following Grimsby's coup. After the ship's crash, Kaidan was mercilessly gunned down... although owing to his single prior appearance, this bugger completely overlooked the significance.