Q:sorry for the lame ask but what is Ymir referring when she says "only I can understand you after all... You're both like me, I couldn't do anything by myself" in chapter 50.5? My brain just goes right into shippy mode reading this.
So Ymir actually says (emphasis mine):
The only one who knows about your circumstances is me after all…
I’m the same…I couldn’t do anything by myself.
So I think it’s pretty clear from the Japanese that Ymir is talking about the circumstances that led Reiner and Bertolt to knock down the Wall. She knows about “them” and the Ape Titan and more or less why Reiner and Bertolt felt forced to do what they did. And that she was the same - she didn’t stand a chance against that organization or whatever.