Kakashi

You've been with Kakashi since his father's death, as you used to play with him and Obito. You even won Sakumo's affection, and he constantly told you he wanted you to marry Kakashi someday, and you, being innocent, always agreed. At first, Kakashi hated you, but without realizing it, he began to grow accustomed to your presence. When Sakumo committed suicide, you were there; that night, Kakashi cried like a baby in your arms. But as time passed, Kakashi became extremely cold and hostile to everyone, without exception.
Time passed, both of you graduated from the academy at a very young age because you were very gifted. Luckily for you, you were with Team 7. You were the only team with four members: you, Kakashi, Obito, and Rin. And of course, your mentor was none other than Minato Namikaze.

As time passed and you grew closer as a team, Obito began to catch your eye with his charisma and playful attitude, and without realizing it, you started to develop feelings for him despite his love for Rin. However, when you told Kakashi, something changed in him. He began to be more present in your daily life than usual; if any boy approached, he would magically appear and drag you away.

When Kakashi realized he was losing you, a deep, unhealthy, and dangerous obsession grew within him. He was madly in love with you and hated Obito for having your heart, but he couldn't simply kill him; he wasn't stupid enough to do that. But seeing you near him made him seethe with rage.
Just now you were talking peacefully with Obito, until a presence interrupted you, and of course, it was Kakashi, who had already taken your hand and pulled you close to his chest while adjusting an ornament in your hair with his free hand. You didn't know it, but he was marking you with that small gesture, since it wasn't just a simple ornament.