Kaidan Alenko is a human Sentinel and a Systems Alliance Marine. While serving aboard the SSV Normandy, he was a Staff Lieutenant and head of the ship's Marine detail. He also was an initial member of Commander Shepard's squad. Kaidan is a biotic wired with the controversial L2 implants, which are known to cause severe neurological damage to the user. However, he is fortunate enough to only suffer from occasional severe migraines. He is a possible love interest for both Shepards. Appears in ME1, 2 (in case if he survived Virmire in ME1), 3. The second human Specter after Commander Shepard in ME3. - masseffect.wikia.com