Kaidan Alenko returns to Mass Effect 3 as a squad member and potential romantic partner for those playing as any gender, as long as he survived the events of the first game. He doesn't need to have been romanced previously in the Mass Effect: Legendary Edition collection. Although continuing a relationship will change their interactions with each other early in the third game.
It's also possible for Kaidan to die during a key story moment, so it's important to make a lot of correct decisions in order to keep him alive and continue a relationship with him to the end of Mass Effect: Legendary Edition.
RELATED: Mass Effect 3: How Long Is It
Kaidan appears right at the beginning of the game, but these dialogue options have no repercussions. Feel free to choose any response. During the first conversation the pair have on Mars about Shepard's ties with Cerberus in Mass Effect 3, respond with "You know me better than that". During the next conversation regarding Cerberus, pick "How can you say that?" and "I never left".
Buy the TM88 - Peruvian Whiskey from Sirta Supplies at the Huerta Memorial Hospital and give it to a recovering Kaidan to get some bonus dialogue with him when they next speak. This will occur when Kaidan sends a message to Shepard's private terminal after another mission has been completed.
During the conversation with Kaidan after he wakes up, make sure to pick "Yeah" if he asks if they are good, and apologize and choose him over another character romanced in the second game. After the conversation, leave to complete one more mission in order to get another message from Kaidan. Return to the Citadel and speak with him again.
Cerberus and Udina will attempt a coup as part of "The Citadel II" mission after
Read more on gamerant.com