One key event was his father's death. It made him grow up quickly. Another was getting the Sharingan from Obito during a battle. His time in the Anbu was also crucial as it shaped his character. And of course, becoming a teacher to Team 7 was a significant part of his life.
Kakashi's life story is full of hardships and growth. He was a prodigy in Konoha. As a child, he witnessed the death of his father, which had a profound impact on him. He became a ninja and was part of the Anbu. His experiences there toughened him up. Later, he became a teacher to Naruto, Sasuke, and Sakura, guiding them in their ninja journey.
Their daily life would probably be filled with quiet moments. Kakashi, being a private person, would enjoy simple things like having tea with Hanare in the morning. Hanare, on the other hand, might be more outgoing and try to get Kakashi to socialize more with their friends in the village. They would also train together, with Kakashi teaching Hanare some of his signature jutsu.
If Tsunade and Kakashi were married in a fanfic, it could be a really unique relationship. Tsunade is a powerful medical ninja and the Hokage, and Kakashi is a highly skilled shinobi. They would support each other in battles. Tsunade could heal Kakashi's wounds quickly, and Kakashi could use his Sharingan and combat skills to protect Tsunade. In their daily life, they would respect each other's space. Since they both have lost people they love in the past, they would find comfort in each other's company. Maybe they would travel together during their vacations to places they have always wanted to see, like the hot springs in some far - off land.
Often, Gai is paired with Kakashi in Hurt Kakashi fanfiction. Gai, with his unwavering belief in friendship and his eternal rivalry with Kakashi, can be a great character to interact with a hurt Kakashi. He might try to pull Kakashi out of his slump through their friendly competition. Also, Rin is sometimes included. Since she has a significant past with Kakashi, her presence in the fanfiction can either be a source of comfort or more pain, depending on how the story is written.
In such fanfiction, the Kakashi OC often has unique physical features. For example, they might have distinct hair color or eye shape that sets them apart.
Kakashi might be initially surprised. But then, he would probably use it as a teaching moment for Naruto. He could say something like 'Naruto, stealing is not the way of a ninja.' And then give him a punishment like extra training.
Often, Naruto is paired with Kakashi in such fanfictions. Their bond from the original series can be explored in new ways in the context of Kakashi's reincarnation. For example, Naruto might be the one to discover Kakashi's reincarnated form and help him adjust.
Kakashi could use his Sharingan to analyze Obito's moves and find a weakness in his defenses. Since he has the Sharingan, he might be able to predict Obito's attacks and counter them effectively, eventually finding an opportunity to break free.
Kakashi's reaction would be complex. He is a man who has lost many people in his life. But Naruto was special. He would hold Naruto tightly, his hands trembling slightly. He might try to use some of his own chakra to keep Naruto alive a little longer, but deep down he knows it's futile. His face would show a mixture of pain, regret, and love. He would remember all the times he trained Naruto, all the lessons he taught him, and how Naruto had surpassed all expectations.