WARNING!!! SPOILERS AHEAD!!!

FUJIMIYA AYA

Fujimiya Aya, like all Weiss characters is not without his "issues"... he's not only concieved as a cold-hearted obsessive character, his entire character seems to revolve around his sister and avenging his parents (which is understandable... right?).

Aya, as is revealed in both the series and the manga, is not Aya's real name, in truth, his real name is actually Ran. After the accident which put his sister "Aya" into a coma he took one of his sister's earrings as a reminder of her and swore to avenge both her and thier parents... At one point in the manga, Yoji asks Ran what his name is and jokes "Are we supposed to call you Aya from now on?" (not a literal translation... i think) Ran accepts the name making him "Aya" from then on.

Taketori Reiji was a business associate of Aya and Ran's parents. Apparently something happened in their dealings that he killed both their parents and tried to kill Aya and Ran in the meantime. The manga is different from the series in that in the manga, A bomb was what killed their parents and put Aya in a coma. In the television series, Their parents were found dead after a carnival where they bought Aya's earrings (for her 16th birthday). A car accident then rendered Aya comatose in the series. Aya could see Taketori Reiji's face through the window of the car.

Not long after his sister's accident (and need i mention the death of his parents) Ran was recruited into, as far as i can tell, Crashers, which is a Kritiker organization... and after Crashers, he was recruited into Weiss... as the last of the four members to join.

For those that have gotten to the dramatic precious albums, Shion is the person who trained Ran with the sword and was also Aya's mentor.