The name says it all. A sporadically popular franchise that brings two of the most mythologised and infamous asari demographics together, featuring an Ardat-Yakshi (so far as the condition is understood by the general public) who becomes a Justicar. Any actual resemblance to real Ardat-Yakshi or actual Justicars is rare and entirely coincidental.
The franchise began as a series of novels, and has been adapted to HV more than once, most recently shortly after the Reaper War.
Jayheena, an Ardat-Yakshi, is the only survivor after a planetary catastrophe. She desperately tries to find her mother, who locked her away as a small child and abandoned her, resolved to have her revenge no matter the cost. However, while she is about to kill a man on the space liner she travels on she is interrupted by the cute foster child of her would-be victim (in the original, child and father are salarian and the child is male, in the recent remake child and father are human and the child is female).
The encounter changes her and instead of seeking vengeance, she realizes that there are people like her who need protection. Jayheena travels to Thessia under a new identity to become the Ardat-Yakshi Justicar.
As for the appeal of the premise, director Jen Haderia opined that both Justicars and Ardat-Yakshi "symbolize an unattainable sexual desire in the face of death, a subject that never gets old."