History

Alyssa was turned at an unspecified time in the past or when she became leader of the vampire house/group known as Siren Sect. She also became romantically involved with Xarus, the son of Dracula.  
 

Vampire Gathering

 
Alyssa and her sect attended the gathering of vampires that took place once every century. She did not participate in the staking of Dracula in the meeting. Consequently, Alyssa suggested ideas of opposing Xarus to his older brother, Janus. It is unknown how involved she was with Xarus' plans as she later sends three of her underlings to please Xarus and later kill him, failing. After Xarus threatenned the Siren Sect, Alyssa agreed to help him but once again secretly helped Janus escape when Xarus tried to execute him by daylight.
 

Powers and abilities

Alyssa has the standard abilities of a vampire in addition to the powers unique to the Siren Sect of female vampires.  She apparently possesses certain empathic/hypnotic abilities that even Janus claimed to be powerful.