Ymir and Connie’s friendship isn’t talked about enough in the snk fandom.
Ymir acts like a jerk who doesn’t care and the only one who gives her shit right back to her is Connie who isn’t afraid to call her out on any of her bullshit. Ymir’s only friend/girlfriend is Krista but as the series went on Connie is the only other one who’s somewhat close to her. Krista was ready to throw her life away for Ymir and she didn’t think she cared about her until Connie convinced her and made her realize that everything Ymir does is to protect her. After the events at castle Utguard, the survey corps and the entire military was ready to take Ymir as a prisoner until Connie convinced everyone that she was an ally on their side so Hanji immediately made plans to get her medical attention and the best and most proper care asap. And even though Ymir is the one who “brushes everything off” with a whatever attitude, she felt bad about Connie’s mom. Go back and look at her face when she tries to get Connie to change the subject. She may not show it directly but she does care about him too. She knows that he’s the reason why Krista realized how she felt about her. They have that type of friendship where they give each other shit, call each other on their bullshit and they’re the only ones allowed to call each other names and won’t tolerate any one else doing it.