Initially presented as a heterosexual love interest for a female Shepard in the first game, the character is reintroduced in Mass Effect 3 as a bisexual love interest, a decision by BioWare which attracted mostly praise as well as some criticism. In Mass Effect 3, Kaidan initially appears at the Alliance base in Vancouver before taking off on a mission to Mars with Shepard and the crew of the Normandy SR-2. If Kaidan survives the events of Mass Effect, by the events of Mass Effect 2 he is encountered on the human colony of Horizon after Shepard receives a tip that Horizon will be the next human colony to be abducted by the enigmatic race known as the Collectors. Kaidan's fate on the planet Virmire is part of a pivotal decision which the player has to make in order to advance the narrative. The character is initially introduced in the original Mass Effect as a human Systems Alliance Officer and primary squad member in Commander Shepard's team.

Kaidan Alenko is a fictional character in BioWare's Mass Effect franchise, who acts as a party member (or 'squadmate') in the first and third games in the series. Kaidan's design in Mass Effect 3, as presented in The Art of the Mass Effect Universe