Shingeki no Kyojin: The Final Season Episode 9 is now available and it highlights a flash back story of how Yelena become a loyal follower of Zeke. The anime features the continuation of the arrival of the Survey corps after their raid on Marley.
In the episode, we have seen how Yelena managed to join and become an ally of Paradis Island. He helped Levi and the other Survey Corps defeat the enemies approaching the island by tricking them.
During Yelena’s first encounter with the Paradis Island devils, she killed one of the officers of their ship. She was helped by her fellow Anti-Marleyan Volunteers on dealing the other clueless soldiers of the Marley.
As they talk inside the tent, Yelena revealed more information about the military power of Marley. And at the same time, we got to know how she becomes a loyal follower of Zeke Yeager.
According to Yelena, she and his comrades found themselves almost completely defeated to rebel against Marley. But before she got killed, Zeke Yeager appeared in front of them and saved them using his Titan form. Zeke’s appearance rejuvenates their will to fight and it also inspires Yelena and also considered Zeke as a God.
Following that incident, Yelena started her journey as an Anti-Marleyan Volunteer and helped Zeke on his plans. She followed every word that Zeke told her, including their plan during the raid in Marley, where they acquired the War Hammer Titan.