In Bleach TYBW, even Yhwach, the son of the Soul King and the Father of the Quincy, who is the Shinigami's ultimate enemy, does not want to make an enemy of Aizen. After his defeat to Ichigo Kurosaki several months before the events of Bleach TYBW, the former Captain of the 5th Division remains imprisoned in the Central Underground Great Prison beneath the First Division's barracks.
After his shocking betrayal of the Shinigami, Aizen will always be remembered as one of the most memorable villains in the world of manga and anime. It is no surprise that Yhwach reveres him and invited him to join him.
Disclaimer: This article contains spoilers from the Bleach TYBW arc.
Yhwach is apprehensive about Aizen in Bleach TYBW
Why did Yhwach go to see Aizen?
Yhwach went on a hiring spree in the manga, recruiting everyone from Arrancars to Uryu Ishida. There was a flashback scene in Bleach TYBW episode 6 where fans saw Yhwach visit Aizen in his prison cell and asked him to join the Wandenreich.
Yhwach invited Aizen to join him because he considers him a special threat, which is significant given that Yhwach declared Captain Commander Yamamoto was not a threat to him shortly after their meeting. Aizen is a threat because he is presently invincible as a result of fusing with Hogyoku. Yhwach believes he can kill or restrain him, but he does not want to waste time because it will take too long.
Furthermore, he wields an extremely dangerous Zanpakuto, Kyoka Suigetsu, which grants him the power to gain control of the enemy's sensory experience, resulting in hallucinations that are indistinguishable from reality. Even while imprisoned and immobile, he was able to befuddle Yhwach's sense of time.
When embarking on an ambitious but perilous mission, Yhwach was correct in believing that making friends with a potentially dangerous enemy is a far better decision than leaving everything to chance. Readers of the manga are already aware that Aizen will play an important role in Soul Society's battle against Yhwach and his Quincy army in the anime.
Why did Aizen reject Yhwach's offer in Bleach TYBW?
In Bleach TYBW, Aizen was unpredictable in Yhwach's plans, but he believed that if both of them wanted the downfall of Soul Society, they could join forces. When Aizen refused to obey him, he was visibly taken aback.
Aizen may be one of Soul Society's most vehement opponents, but he sincerely disagrees with Yhwach.
In manga, he said that the world that Yhwach wants to create by collapsing the three realms and removing all fear will not work. Fear, he claimed, is not a burden, and there would be no hope in a world without it. He believed that overcoming one's fears and persevering with courage in the face of death is far more powerful than simply living.
