That was certainly… interesting. One can always get a sense that Shingeki no Kyoujin is trolling the audience, but it certainly applies in force to the events of this episode. So much so that it almost felt like taunting – “See, we’ve given you so much information, and you haven’t figured it out yet? What a bunch of idiots!”
What strikes me is that the narrative at the moment feels disjointed. There’s just a lot of weird stuff going on that gives the impression that things were just thrown together – the pacing is uneven from episode to episode, and the key dialogue scenes (like Reiner’s “confession” to Eren and the dialogue between he and Ymir this week) are flat-out strange. I can only assume this is how it’s supposed to be, but for all its whacked-out craziness the first season seemed to have much more of a flow to it (apart from that endless time loop in Trost) than this one.
There were several new revelations this week, though in classic Attack on Titan fashion they raise more questions than they answer. We heard Reiner use the word “Coordinate” for what I believe is the first time (I suppose it’s possible it’s not and I just forgot), and context suggests it’s something quite critical to the conspiracy (and Christa’s role in it). We also heard Ymir say she’d been wandering around outside the walls for 60 years, which opens up a whole can of worms about the titan conspiracy as she sure doesn’t look it. Ymir, Reiner, Bertolt and Eren have apparently all eaten humans – and none of them remember it (so who did Eren eat, then? Did we see it happen?). And it was pretty much confirmed that the titan in Conny’s village is, in fact, Conny’s mother – or at least the woman he believes is his mother.
The big infodump, though, was Ymir’s backstory. She was snatched from a destitute village and stuck on a throne in a nest of cultists, supposedly with “the blood of the king” flowing their her veins. The impression here is that her kidnappers never believed that Ymir specifically has any such distinction – she was just a child who suited their needs for whatever reason. Believers were told they would be given immortality (yeah, that seems like an important clue), but when the cult was raided and the lot of them executed that was put to the lie. For some reason at that point Ymir turned into a titan and began her 60 years of wandering (and lying underground).
I’m honestly not sure how all this fits together, but in the moment what matters is that the scouts have arrived and forced Reiner and Bertholt to change their plans and bolt. After a brief freak-out by Eren is subdued the foursome of titan-humans does just that, but Ymir isn’t going along with the plan because she knows Christa is among the soldiers chasing them. I think Ymir is prepared to go along with Reiner’s larger plan, which is to return to their village, but only if Christa is along for the ride. And she’s not prepared to accept his plea to wait for a better moment to try and snatch her, forcing Reiner to adopt a highly risky scheme to snatch Christa from under the noses of the pursuing enemy.
I’m happy to speculate for now, to try and piece together the clues from the episode and the possible hints in the OP. But I do hope we get something definitive before the end of the season, otherwise there won’t be much of a sense of progress here. It still seems likely we’ll get at least a third season of Shingeki no Kyoujin, even with a huge drop in disc sales, so obviously we’re not headed for some sort of comprehensive anime-original ending. But it would be nice to leave off with at least part of the mystery revealed in something more than abstract clues and foreshadowing.