In true Attack on Titan momentum-killing fashion, we cut away from Titan-Ymir’s impending brawl with the other Titans to the fateful night Krista and Ymir shared back during Winter Training. There, it wasn’t Titans that threatened their lives, but the freezing cold of the blizzard they found themselves caught in.
Krista is determined to drag their injured comrade Daz back with them, but he’s half-dead already, and he’s slowing them down so much they may all freeze before returning to base. No, Ymir doesn’t think Krista is trying to save Daz. She thinks she’s trying to end her own life and pass it off as heroism.
In a flashback within the flashback, we learn why, and the root of Ymir’s interest in Krista: she learned that Krista was the illegitimate child of a noble, and thus ineligible to succeed him. Rather than just killing her, they changed her name and forced her into the cadets. Considering Krista a kind of kindred spirit, Ymir doesn’t think Krista should make the people who cast her aside happy by dying just yet.
As the flash indicates, Ymir transforms into a Titan to carry Daz back to base, having conveniently buried Krista in the snow. By the time Krista returns to base on her own, she’s stunned to find Ymir and an alive Daz beat her there. She asks Ymir how the hell it’s possible, and Ymir tells her…but only if she keeps an important promise.
Back in the present, it would seem that Krista either Ymir’s secret, after being plied with wine by Ymir shortly after learning the news. As it happens, Reiner and Bertholdt’s friend was killed by Titan-Ymir, so for a moment Reiner takes his blind rage out on Krista’s slender leg, before pleading ignorance of Ymir’s secret form.
Meanwhile, Titan-Ymir is kicking ass, but in her efforts to keep the tower from falling, is at a distinct disadvantage. You can’t play offense and defense at the same time, and noticing Ymir’s attempted heroics, insists that Ymir not die here, and instead tear the dang tower down, which she does. After that, everyone grabs Ymir’s hair and she flies them to safety.
“Safety” being out of range of the crumbling tower, but once all the stunned Titans get back up, they find themselves sitting ducks. There’s a horrifying oment when a Titan confronts Krista and goes for her head, but just then, Mikasa blazes in to take the beast down.
The cavalry has arrived, and their arrival brings a huge jolt of adrenaline to what had become an increasingly hopeless scenario. Eren even manages to sneak in “his first kill”, though I assume he’s talking “as a scout”, as he’s killed plenty as a Titan.
Once the remaining Titans are mopped up, everyone turns to Ymir, who has returned to human form, but is in rough shape. Krista talks hold of her and fulfills her promise, telling Ymir her true name: Historia. Then Ymir closes her eyes and smiles.
While I’m not left 100% sure this means Ymir is dead, with missing limbs, and a chest wound, she’s certainly not fighting anytime soon. Still, it was another emotional journey that deepens two more scouts, even as it seemingly takes one of them away.
Ymir clearly isn’t a saint (from the looks of what she did to Reiner’s village) but she’s not quite the devil, either. She decided long ago she’d go her own way, and that way included supporting Krista whenever she could, even at the cost of her life.
And Krista, who never made that deep of an impression in the first season (though I briefly mistook her, not Annie, being the Female Titan) really comes to life, both through her backstory and the passion she exudes. That character work makes this a solid outing, despite not touching on any of the show’s other, arguably larger extant mysteries.