Princess Selene and Prince Orion. They were both taken from their family at very young ages by Hecate. Selene was 3 and Orion was 5. They grew up under Hecate's tyranny, and their lives were anything but happy. The only things that kept them wanting to go on, were their hatred of their siblings (Usagi and Mamoru) and their love for each other. They travelled to earth with Hecate, thinking that they would take their true places as rulers of the Earth and Moon. However... Hecate had a quite different agenda.
About Orion:
Prince Orion is a hot tempered, strong, playful, and romantic fellow. He is constantly getting into fights with Hecate and constantly being fried for that. He hates Hecate with a passion, and always went out of his way to make fun of Hecate. Once, when Hecate hit Selene, Orion vowed to get revenge on him. Orion loves Selene very much, and if anyone hurts her, it is a pretty sure thing that they'll pay. Orion is a lot like Seiya in a couple ways. Orion went by the name of Kurabara Motsu in class, which means "Carries the Dark Roses."
About Selene:
Princess Selene is what you would expect from a princess. Unlike Serenity, Selene is calm and collected, very talented and regal. She plays a harp, which she somehow managed to take with her from when she was kidnapped. She always plays sad songs, for that is how she usually feels. Selene didn't think the rest of the senshi should suffer for Serenity and Endymion's betrayal. Selene went by the name of "Katsu Yami" in class, which means "Victorious Darkness."
Orion is from mythology as well, a mythological lover of the goddess of the moon, Selene. Makes sense, ne?
Orion's dice were 2d20 for slashing with his sword, and 2d25 for a "Sword Blast" where he shot dark energy from the sword. If he was angered, he could charge his sword with dark energy. and up his dice to 2d27. He also threw dark blue roses which were 2d18. (It's a classic case of Red vs. Blue, like in my favorite anime ^_^)
Selene's dice were 2d20 for shooting dark energy from her harp. She could also charge her harp, to make it 2d22. She had a dark moon wand, just as Sailor Moon has a regular moon wand, which was 2d25. But she didn't use it ever.
A few words from Orion & Selene :
"Orion... I still don't like this..."--Selene
"It was the continuation of the endless struggle, between the sadness of blue and the pain of red." --Fushigi Yuugi
"Sayonara, fat boy!"--Orion
"You're about as big as a barn!"--Orion
"Sayonara.. Serenity..."--Selene