Renji
Abarai

Renji Abarai grew up in the same Rukongai slum as Rukia Kuchiki, watched their other friends die, and entered the Shinigami academy with her as the only family he had. Then the Kuchiki clan adopted her, and Renji spent the next forty years clawing his way up to lieutenant of the 6th Division, directly under Byakuya, measuring himself against a nobleman he could not beat, all so he could one day stand close enough to take her back.

The show introduces him as an enemy. He comes to Karakura Town to arrest Rukia, mocks Ichigo, and loses to him twice, and the second loss breaks him open: bleeding on the ground, he begs Ichigo to save the woman he was sent to condemn. His fight against Byakuya during the rescue, Bankai against Bankai, ends with Zabimaru shattered and Renji still crawling forward, which is the most Renji image the series ever produces.

From there he settles into being Ichigo's rival, comic foil, and most reliable backup, fighting Espada in Hueco Mundo and training with the Royal Guard during the Blood War. Oetsu Nimaiya tells him his Bankai was never complete because he flinched from its true name; the finished form, Soo Zabimaru, disintegrates Mask De Masculine in one exchange. In Wahrwelt, Uryu shoots him through the chest and leaves him for dead, but the Visored patch him up, and he arrives back on the field by snagging Gerard Valkyrie's arm mid-boast, telling the captains to leave the giant to him.