Preference: Females, but makes an exception for male Shepard in ME3
Personality: Stoic, thoughtful, vanilla
The human biotic with a dark past is back in Mass Effect 3, assuming you chose to keep him alive during the events of Mass Effect 1. In Mass Effect 3, Kaidan has the extremely awesome task of commanding a biotic-based covert ops unit for the Alliance, though he is quick to join Shepard and fight for the galaxy when the Reapers invade Earth.
Note: Kaidan’s role in Mass Effect 3 is virtually identical to Ashley’s, as are the steps to romancing him.
Previously, on Mass Effect
Both new and imported female and male Shepards can romance Kaidan, but in the case of females, actions taken in previous games can complicate things. Kaidan will be suspicious of your motives early on in the game regardless of any previous relationships, but this resentment is multiplied if you ‘cheated’ on him during the second game. If that’s the case for you, make sure to follow the guide below carefully.
Kaidan is part of your squad for the Priority: Mars mission, and it’s during this time he’ll repeatedly bring up Shepard’s prior relationship with Cerberus. Avoid the aggressive Renegade responses, especially if you’re making up for being unfaithful in the second game.
There’s no way to prevent Kaidan from getting injured on Mars. He will be laid up in the hospital for a good chunk of the game, so it’s important to visit him when opportunities arise.
When you go to the Citadel after the Mars mission, make sure to stop by the hospital. While not absolutely necessary, you should also visit Sirta Supplies on your way and purchase the Peruvian whiskey gift for Kaidan. He’s unconscious at this time, but it will come in handy later. Don’t worry about specific dialog choices here; he can’t hear you.
After the Priority: Palaven mission, you should get a private message from Kaidan, who is awake and willing to see you. Now is your opportunity to present him with that whiskey, and you should be generally supportive here in order to regain his trust.
Above: No man... I*hic* love YOU
Kaidan will be back on his feet during the Tuchanka missions, and he’ll once again extend an invite via private message. It’s important that you visit him again at this time and continue the supportive dialog, or things could get quite messy the next time you two encounter each other.
At the end of the Priority: Citadel mission, Kaidan will be escorting Udina and end up in a standoff with Shepard. If you’ve done everything you can so far to nurture your relationship with Kaidan, you can get him to stand down very easily (if you are playing an imported Shepard), or with one bar of reputation (if you are playing new). If you can’t get Kaidan to stand down here, things get pretty ugly, and the road to romance will end.
There is a forced encounter with Kaidan just before returning to the Normandy. It’s here that you actually convince him to stay on your crew. He’ll gladly join if you’ve been friendly so far; if not, it will take some serious reputation points to convince him. It should go without saying that he needs to be on your crew if you wish to see this romance through. As soon as you’re back on the Normandy, pay a quick visit to the starboard observation deck and have a chat with Kaidan.
Closing the deal
After the Priority: Geth Dreadnought mission, Kaidan will send you a private message inviting you to dinner with him at the café on the Citadel. Choose favorable responses here and things will be all but wrapped up.
The real reason you’re here:
Once you’ve chosen to go ahead with the Priority: Cerberus Headquarters mission, the following scene between Shepard and Kaidan will take place: