Bleach mainly revolves around shonen hero Ichigo Kurosaki, whose life changed one night when Rukia Kuchiki granted him her Soul Reaper powers to defeat a monstrous Hollow. Before long, Rukia's childhood friend and fellow Soul Reaper Renji Abarai arrived on the scene with his own pivotal role to play in the story.
Renji was first introduced as a villain, a thuggish Soul Reaper who had been tasked with dragging Rukia back to the Soul Society to await twisted justice. He was the Lieutenant of Squad 6, serving under Captain Byakuya Kuchiki, and his personal story was soon fleshed out in the Soul Society arc. There's much more to Renji than his rivalry with Ichigo, and these five scenes and events define the person he became in the end.
When Renji's Childhood Friend Decided To Become A Soul Reaper
Rukia and Renji had known each other since childhood, both being fellow street urchins in the Rukongai district. They were part of a whole pack of troublemaking kids, committing petty theft to scrape by in what was a bitter and dead-end life. However, Rukia had a remarkable talent for kido spells, and Renji wasn't unskilled himself.
Since there was truly nothing left for her in the Rukongai district -- especially after her friends had died -- Rukia decided to apply to the Shino Academy to become a Soul Reaper. Renji felt the same way and followed her lead in joining Shino as a proper student. Both of them were on a proper path now, and Renji owed it all to Rukia.
When Renji Lost To Ichigo During Their Rematch
Fast forward to the main events of Bleach, and Renji is functionally a villain. He is loyal to his Captain and must stop Ichigo out of duty, but Renji is not evil at all -- in fact, he secretly resents having to defend Rukia's unfair death sentence. When he and Ichigo had their rematch in the Soul Society, Renji fought only for duty, not pride, with his zanpakuto (Zabimaru) in hand.
Ichigo narrowly won, while Renji, who could no longer serve his duty, had a change of heart. All he had left was his good friend Rukia and, inspired by Ichigo's example, decided her survival was now his top priority. Renji thought back to his Rukongai days with Rukia, and desperately implored Ichigo to save his friend. This put Renji on the path to becoming a proper hero, also planting the seeds of his and Ichigo's future friendship and alliance.
When Renji Stood Up To Captain Byakuya Kuchiki With His Bankai
Renji's quest was not yet complete, however. After being healed, he decided to take a more active role in protecting Rukia from unfair Soul Society law, independent of Ichigo (who was elsewhere). Renji deeply admired his Captain but he could not allow Rukia to die, as he proved by standing up to Byakuya in mortal combat.
Byakuya could hardly believe it, but Renji was ready to risk his life to save Rukia, showing he was quickly becoming Ichigo's equal. What's more, Renji activated one of the most stunning bankai releases in this story arc and put up a great fight until Byakuya finally defeated him. Renji's heart was firmly in the right place, deeply impressing Bleach fans with his brave defiance.
When Renji Unlocked His Final Bankai, So'o Zabimaru
Renji thought he had reached his full potential with his bankai, Hihio Zabimaru, but he was not quite correct. He had been using a partial bankai all this time, which would not be enough to prevail by the time the Sternritter arrived. Renji and Ichigo met Oetsu Nimaiya, the creator of all zanpakuto, and Renji effectively started from scratch to awaken the true Zabimaru.
After learning about Asauchi and the nature of zanpakuto spirits, Renji forged his final bankai and learned its name: So'o Zabimaru. This incredible new power gave him the strength to face Sternritter "S" Mask de Masculine and obliterate him, proving Renji a true master of zanpakuto through and through. No doubt Byakuya was immensely proud of him.
When Renji Married Rukia
Many Bleach fans loved the idea of Ichigo ending up with Rukia, but it wasn't to be. Instead, Ichigo married his childhood friend Orihime Inoue. Ten years after Yhwach's defeat, Renji likewise married his childhood friend Rukia, and as far as Ichigo can see, they're getting along great. Both characters had been through a lot, and now they can find true happiness as comrades and spouses.
Renji has found peace at last, and he has the free time to visit the Kurosakis and have their children meet and play together. Renji is even a family man, having a daughter named Ichika with Rukia, and little Ichika is already powerful and talented like her parents. Any father would be proud of her.