"I'm not sure, really," admitted Mikasa softly. "No one was really made to fight, but...Eren wanted to, for as long as I could remember. So I went to protect him. He saved my life when I was young so that was the least I could do." Gwen's thoughts were along the right lines, but, Mikasa wasn't about to get into the inner workings of their society. She didn't really understand it fully yet, but she had a fairly good grasp of how things worked.
With the hand on her shoulder, Mikasa's gaze softened and she listened to her new friend's thoughts. "Who is this Gideon, if I might ask? Sounds like someone close to you." She managed a brief smile. Usually, the ones closest to someone were the people who could tease them the most. Eren and Armin could be like that on occasion, but they were close like brothers. Though, she did frown thoughtfully, "You were hidden and weren't allowed to do your training? That sounds a bit selfish." Though, she did understand.
She had a suspicion that Dr. Yaeger knew about Eren's Titan-shifting ability, but had kept it hidden from Eren so that he could live normally. Where the man was now, no one really knew. Inside Wall Sina was a good guess, because they hadn't run into him just yet.