The Serena and Darien Romance
Sailor Moon
This romance started 1000 years ago
in the days of the Silver Millennium.
In those days, Serena was princess of the Moon and Darian was prince of
the earth. 
They loved
each other very much, but their love was to be tested. Queen Beryl, ruler of an evil realm called
the Negaverse, escaped from her realm to ours.
In order to take over the universe, she first had to conquer to Moon Kingdom. When Queen Beryl and her warriors started
terrorizing the Moon, everyone from the Moon Kingdom accused the people from
earth, including Prince Darian, Serena’s love interest. But the prince came back to the Moon to
protect the love of his life.
Darian told Serena that he is going
to fight in the battle to protect her kingdom and that he might get killed in
the battle. So Princess Serena gave
Prince Darian her star locket so that he will not forget her. Then Darian went to fight Queen Beryl and
her warriors. Serena saw Queen Beryl
attacking Prince Darian and went after him.
Unfortunately, they both died.
But 
Queen
Serenity, Princess Serena’s mother, used the imperium silver crystal to send
her daughter, Prince Darian, and the Sailor Scouts(they were also killed in the
battle) to earth to be reborn 1000 years in the future.
When
the anime Sailor Moon starts, Darian and Serena live in Tokyo 1000 years after
the silver Millennium. But they don’t
remember anything about their lives during the Silver Millennium, and they
cannot stand each other. It wasn’t
until the imperium silver crystal revealed that Sailor Moon(Serena) was the
Moon Princess that Luna and the other scouts have been looking for that Serena
remembered that Darien was the love of his life.
But Zoisite had already injured
Darien badly so the Sailor scouts didn’t know he remembered anything because he
was unconscious when everyone found out Serena was the Moon Princess. After it was revealed that Serena was the
Princess, Queen Beryl teleported Darien to her palace. There, she erased all his memories and made
him fight on her side. Serena was
determined to get her Darien back. She
did one time when she used the Moon Crescent Wand on him. But Queen Beryl
teleported him again to her palace and erased his memories and made him fight
on her side again.
Later on in Sailor Moon, Sailor Moon goes to Queen Beryl’s palace. There, she got Darien back to normal by convincing him to touch the Star Locket that she gave him back in the Silver Millennium(Tuxedo Mask gave it to Sailor Moon earlier in the series). When he touched the Star Locket, he had all his memories back. Then Queen Beryl was destroyed and Serena and Darien were free to live a happy life together again.