It is me probably overanalyzing, but I actually really like the small interactions that Mikasa has with Eren during vols 18 – 21. Like putting the cape on his back, putting her hand on Eren’s shoulder and opening the book with Eren.
I like these because I view them as a small change to Mikasa’s and Eren’s dynamic. Before this, most of the time Mikasa has tried to get Eren away from danger, and making it so that it is her who delas with it. “I will protect you.“
I think Eren said that he was jealous of Mikasa’s power, and in a world where power gives you agency, something like Mikasa carrying Eren on her back might have been humiliating.This over protecting is a reminder of Eren’s lack of power, and thus his small amount of agency to affect things and the state of the world.
But this stuff that happens in vols 18 – 21, I think it is the opposite. I view them as something empowering. When Mikasa gives the cape to Eren and he is doupting himself, she says to him that Eren needs to trust his power. I think these are actually quite similar to the scene with Armin. Eren was scared but the chat with Armin gave him courage (the thought of the outside world made him feel, that power is coursing trough him). Mikasa does the same thing in my opinion. By putting her hand on his shoulder, and putting her hand on the book whe Eren is shacking, Mikasa gives him power. Power to do, power to act.
Instead of taking him away from the obstacle/challenge, Mikasa makes Eren aware that she supports him, and is there to help him face the future. So instead of reminding about his lack of agency trougn lack of power, Mikasa empowers Eren. I am here with you, so that we face this together.