Fiore is a yandere from Sailor Moon R: The Movie.
Background[]
When he was a child, he was found by and taken care of by Mamoru Chiba. Mamoru was his only friend and the only human he thought was decent. Before he left, Mamoru gave him a rose as a token of their friendship (it was later revealed that Usagi was the one who gave him the rose). When he returns to Earth, he searches for Mamoru to show him the flower that he found especially for him. He was transformed by the flower and his feelings for Mamoru became warped. He saw Usagi, Mamoru’s girlfriend, as a personal threat, believing that she was trying to take Mamoru away from him.