And It goes both ways..
For Mikasa, this new discovery about herself and origins will certainly trouble her in a way or another, and I’m certain that Levi’s presence will make things a lot easier for her.
Think of how it’ll be great for her to know that she’s not alone in this, that she has a support?
Not someone from her peers, not exactly a friend, someone more mature, someone she can rely on, and can lead her through this unknown path that opened from her past.
She had and will always have Eren and Armin, but her bond with Levi will be different and I think it will help her to mature more and will add a lot to her personality.