I do not own Bleach or its characters. That privilege belongs to Tite Kubo.
He's 15 when he first meets Yuzu Kurosaki. Compared to the rest of her loud and temperamental family she is an oddity of quiet motherly kindness. Compared with her father, brother, and sister, she had almost no spiritual energy. He felt sorry for her in a vague way, the child on the outside never part of the circle of her family's secrets.
He's 17 when she finds him bleeding and dazed from his final confrontation with Kurotsuchi. After the Winter War and the Vandereich, he had at last avenged his sensei and the honor of the Quincy. Yuzu helps him to the clinic where a surprisingly quiet Isshin Kurosaki patched him up. That evening he confesses about the Quincy, Hollows, Soul Reapers, Arrancar, Soul Society, and Hueco Mundo. She quietly takes it all in, with no anger or accusations.
He's 19 when she first manifests her powers as a Quincy. Ichigo turns to him to train her. As he spends more time training with her, he finds her longer the lonely girl on the outside but a beautiful and confidant young woman. A part of him feels uncomfortable looking at her at her that way.
He's 20 when he first kisses her at Inoue and Kurosaki's wedding reception. The groom gives him a black eye that's he left nursing for the rest of the week. He doesn't care about Kurosaki's threats of physical harm. He's not regretting anything.
He's 25 when he proposes over a family dinner. A beaming Yuzu says yes. Kurosaki chokes on his fish as Orihime enthusiastically congratulates them, Karin snorts "finally" while Isshin jumps up and loudly announces that he's getting a second son to his poster before Karin decks him. His only regret for that day is that he's getting Ichigo as a brother-in-law. They're married that fall.
He's 26 when Souken and Masaki are born. Twins it seems run in the family. Yuzu's tired but glowing with happiness. He receives congratulations from virtually everyone he's crossed paths with: Ichigo with Orihime and their son Kazui, Rukia with Renjii and their daughter Ichika, Isshin, Urahara and Yoruichi, Tatsuki and Keigo, Shinji and the Visords, Ganju and Kukaku Shiba, Capts. Toshiro Hitsuguya, Byakuya Kuchiki, and Nemu Kurotsuchi. Even Nelliel and her fraccion drop by with a highly unenthusiastic Grimmjow in tow. Ryuuken shows up briefly to pass along his short congratulations before leaving.
He's 27 when Yhwach returns and Ryuuken dies. He says nothing at the funeral. How can a few words encapsulate an old relationship of bitterness, old regrets, and tentative reconciliations? Even his wedding or the birth of his children was unable to truly bridge the gap. He's never understood Ryuuken and now he never will. As Yuzu holds his hand during the service, he hopes his father can find some measure of peace in death that he lacked in life.
He's 34 when he begins training his son and daughters in the Quincy Arts. He can understand now how his father felt all those years ago when he was training with his grandfather. Still it's the only thing he can do to protect them.
He's 47 when he gives Masaki away at her wedding. Yuzu starts quietly crying during the service and he finds himself tearing up. It's then he first truly feels his age.
He's 49 when his first grandchild is born. Masaki and her husband name him after his great-uncle, Ichigo who's since taken up the Captaincy of Squad 8, immigrating to the Soul Society with Orihime and Kazui. They keep in touch where they can.
He's 88 when Yuzu Ishida passes away in her sleep. She departs for the Soul Society alongside her brother with a quiet farewell. He's left behind to struggle through another decade and a half without her.
Uryuu Ishida is 103 when he dies surrounded by his children, grandchildren, and great-grandchildren. His nephew, Kazui is one who passes his spirit on to the Soul Society. When he wakes up in the 45th district he starts making his way through the Rukongai to reach the Seireitei.
Yuzu's waiting for him at the gate.