A demon named "Lily" was a child of a powerful demon. Born centuries ago, she had a son named Basar and eventually forgot both her father and her original name. Time passed and she had her own children, including her son Basar who was hunted by humans, leading to him burning down their village.
Over time, Lily began calling herself Kthara and began possessing human bodies. Eventually, her father punished her by sealing her away into the body of his current wife, Victoria. She would then be referred to as Mother by her younger siblings, Daimon and Ana Helstrom.
Eventually, Ana freed Victoria from Kthara's grasp by killing Victoria and immediately resuscitating her, though this meant Kthara was free to possess the next marked victim, a young novitiate named Gabriella Rosetti. Rosetti was at that moment preparing for a romantic encounter with Daimon, which Kthara took advantage of, by inserting a piece of Basar into Daimon, rendering him possessed. Kthara then made love with Basar in the bodies of Gabriella and Daimon to conceive a human body for Kthara.
A few days later, Kthara was born into a new body as a result of an accelerated pregnancy. This traumatized her new mother Gabriella, and led to her leaving both Daimon and the Catholic Church. Daimon accepted his daughter with the intent to raise her as a good person so that she would not revert to her original self, presumably giving her his surname as her father.
A month after these events, Kthara was about to go on a boat ride with her uncle, Chris Yen, when her grandfather reminded her of her original self's true name and their true connection, of him being her actual father. The two then departed to find Daimon and Ana and left Yen by himself.
- Due to her aliases of Kthara and Mother, and her real name of Lily, Kthara is most likely a composite of Kthara and Lilith, both of whom are known as the Mother of Demons.
- Due to her current self being the biological daughter of Daimon Helstrom, she may also be a counterpart of Demona Hellstrom.
- Elizabeth Marvel portrayed Kthara in the body of Victoria Helstrom in the Hulu series Helstrom. Fiona Dourif portays Kthara in the body of a previous host in the episode Condemned. Grace Sunar portrays Kthara/Lily's new body.