DarienTuxedo MaskMoonlight KnightPrince Darien
Darien is kind of a jerk, at least in the first season of Sailor Moon before he regains his memories of the Moon Kingdom. He is exceptionally rude to Serena whom he calls "Meatball-Head" or "Odanga-Atama" [Japanese Only] to annoy her. However, that later becomes an affectionate nickname as he remembers the love that they used to share.
Tuxedo Mask is the scout's ally and helper, although they don't know that at first. He throws red roses as an attack and often comes in the middle of a battle offering encouragement and advice and prompting Sailor Moon to stop looking at him with love-eyes and kill the enemy.
The Moonlight Knight is kind of a confusing character. When Darien loses his memories again after being on the Negaverse's side, he still feels deep inside that he has to help the senshi in battle. He somehow astrally projects himself in the disguise of the Moonlight Knight to aid them in battle, and throws white roses as his attack. He also as a sword which he uses like Tuxedo uses his cane. The Moonlight Knight and Darien eventually merge and Darien regains his memories and becomes Tuxedo Mask again.
Prince Darien is the past and future form of Darien. In the Silver Millenium, he was Prince of Earth, and in the future he rules by Neo-Queen Serenity's side, and they have a daughter, Rini. There was also an evil Prince Darien. When Tuxedo Mask was captured by Queen Beryl and Malachite, he was brainwashed into believing he was on the side of the Negaverse, and was Queen Beryl's faithful servant. When he was evil he threw black roses as his attack. Although evil, he still believed in a fair fight and often aided the scouts anyway, against his mistress's wishes.