WARNING: The following contains spoilers for Chapters #128-9 of Attack on Titan, by Hajime Isayama, Dezi Sienty and Alex Ko Ransom, now available in English from Kodansha.
Much like Game of Thrones' final season brought disparate characters together, the Attack on Titan manga's final "five percent" of story is reuniting long-separated allies and enemies. This includes the Nine Titan shifters, whose number grows fewer and fewer as Eren Jeager continues to horde their powers for himself. In Chapters #128-9, fans are treated to the sight of two of the Nine, the Female and Armored Titan, fighting side-by-side at last.
Though long-time comrades in arms, Annie Leonhart, the Female Titan, and Reiner Braun, the Armored Titan, have only recently been featured together in the present-day. Their rejoining follows Eren enacting the rumbling, which has sent hundreds of giant Titans standing dormant in Paradis' walls on a path to trample the continent. United by a common cause, the pair joined the Eldian/Marleyan alliance, whose first mission has been to liberate their Azumbito allies and steal a ship from Paradis' harbor to pursue and stop Eren. When the group came under heavy fire from Eren's fanatical Jaegerists, Annie and Reiner transformed into their Titan forms to provide back-up for their non-Titan friends.
Both Marleyan in nationality, Annie and Reiner were raised as Warrior candidates for the Marleyan army. The Warrior unit is trained for one specific purpose: taking on one of the Nine shifter powers in the nation's possession. For Annie and Reiner, this also meant undertaking an incredibly risky deep-cover mission -- infiltrating the secluded island of Paradis and spending years embedded in Eldian society in order to locate the holder of the Founding Titan. Annie was eventually outed, defeated by Eren's Attack Titan and, until very recently in the manga, was encased in a crystal husk deep underground for her own protection. Reiner, along with Bertolt, the Colossal Titan, continued the mission in her absence, following Zeke, the Beast's Titan's directives.
Since reawakening, Annie has abandoned her post in favor of returning to her father in Liberio, the Marleyan ghetto, in time to save him from the rumbling. Reiner, who returned to Liberio a changed man four years ago, has taken longer to break free of his anti-Eldian programming, but he too joined the fight to prevent Eren's genocidal plan. That's why seeing the pair working together to save the world is so rewarding, not just for the inherent fan service of any of the Nine teaming up, but as the culmination of over a hundred chapters' worth of character development.
More so, they use their powers defensively more than offensively. Though the Female and Armored Titan have reputations as brawlers in Attack on Titan, this battle reminds us, thanks to their hardening techniques, of how useful their virtually impenetrable skins are. As the Azumbito make their escape, the Titans use themselves as living shields, almost being shot to pieces by Thunder Spears in the process. Reiner even shields Annie herself from harm, a testament to their close bond after years apart.
Considering the devastation that Annie and Reiner brought to Paradis' shores, their selflessness in this confrontation puts them firmly on redemptive paths.