One of the key elements is the sacrifice he made for the village. He gave up his own family and his own place in the village. Also, the fact that he couldn't tell Sasuke the truth for a long time added to the sadness. He had to watch Sasuke grow up hating him, while he was actually looking out for him all along. And the way he had to live a double life, as a rogue ninja while secretly being a village protector, was also very sad.
The main sad element is the massacre of his clan. He had to kill his own family and friends. Another is his false reputation. People thought he was a cruel murderer when he was actually a protector. And his relationship with Sasuke. He had to lie to Sasuke and make Sasuke hate him, which is really sad.
Itachi Uchiha's sad tale is heart - wrenching. He was a prodigy in the Uchiha clan. However, due to the political situation between the Uchiha clan and the Hidden Leaf Village, he was given an impossible task. He had to kill his own kin to prevent a civil war. This act not only burdened him with guilt but also made him an outcast. His relationship with Sasuke was also deeply affected. He had to pretend to be a heartless killer in front of Sasuke, all while loving his brother deeply. He endured so much pain, both physical and mental, until his death, and his story is a tragic one of loyalty and sacrifice.
Itachi is also a very mysterious character. When he's placed in different settings through crossovers, it opens up a whole new world of possibilities. For example, in a crossover with a post - apocalyptic world, his survival skills and combat expertise would be put to the test in a completely different way than in the Naruto world. This contrast is what attracts many readers.
One main theme is sacrifice. Itachi sacrificed his own reputation and relationship with his family and clan for the greater good of the village. Another theme is loyalty, as he was loyal to the Hidden Leaf even though his clan was planning a coup. And there's also the theme of redemption, as he tried to make up for his actions in his own way.
One element is the sense of loss. For example, when someone loses a loved one, like in the story of the family losing their dog. It's a sudden void that can't be easily filled. Another is shattered dreams, like the girl who couldn't dance anymore. It's the destruction of a future one has envisioned.
One of the key events was the Uchiha clan's planned coup which led Itachi to make the extreme decision of wiping out the clan. His encounter with Obito Uchiha, who helped him in the massacre, was significant. Then, his time in the Akatsuki where he carried out various missions. And of course, his numerous confrontations with Sasuke which shaped both of their fates.
Let's imagine Itachi Uchiha in love with a fellow Uchiha. They grew up together, trained together. Their love was based on a deep understanding of each other's pain and power. But when the Uchiha clan's fate was at stake, Itachi had to make difficult choices. His love for her was strong, but his loyalty to the village made him do things that seemed to shatter their relationship. In the end, his love remained in his heart, a hidden and painful memory.
The contrast. When something unexpected and humorous happens in a sad situation or vice versa, it catches our attention. For example, in a story where a person loses their job (sad) but then finds a new and better opportunity in the most comical way, like accidentally bumping into the boss of a new company at a park and getting hired on the spot.
Isolation is a key factor. When a character is all alone in their suffering, it intensifies the sadness. For instance, an elderly person in a nursing home who has no visitors. They feel forgotten and unloved. Their loneliness seeps through the story and makes it really sad. The lack of hope is another. If a story shows no way out for the characters, it leaves a heavy feeling in the reader's heart.
The most important event was him killing his clan. This changed everything for him and Sasuke. Another one was joining the Akatsuki. It put him in a new and dangerous situation.
In an Itachi Uchiha love story, Itachi could be in love with a foreign diplomat who visits Konoha. They have a whirlwind romance. However, his status as an Uchiha and the secrets he holds start to create problems. His love is tested when his clan's actions put the village in danger. He has to decide whether to side with his love or with his village, leading to a complex and tragic love plot.