Selene is depicted as a beautiful young witch, with "platinum blond" hair and "sleepy blue eyes". She is also said to "move with languid grace", and usually speaks softly and torpidly. She often wears "the darkest robes" alongside Vivienne at Circle Midnight meetings, although she has also been known to wear violet, which "showed off her blondness", and silver for the Samhain celebration.
In contrast to Vivienne's noted energy, Selene is shown to have an opposite temperament, being somewhat "languid" and unhurried, seemingly unperturbed by events around her.
Although Selene has something of a reputation as a darker witch, and concurs with Blaise Harman's view of human boys as nothing more than playthings, both she and Vivienne are deeply disturbed by the Harman girl's antics and their devastating effects; Selene's nonchalant regard for events is only maintained until something troublesome has occurred. Like her fellow witches, Selene is shown to be kind and supportive of her own, helping encourage Thea Harman when she attempts to go after Eric Ross (though Selene is under the impression Thea is only using Eric for entertainment).
Selene first appears in the high school lunchroom; to Thea's dismay, both Vivienne and Selene have befriended Blaise, the three of them having a reptuation for trouble. Selene is willing to participate in Blaise's scheme to acquire the blood of human boys they intend to use spells on, remarking on Eric's cuteness, although nobody has "gotten anywhere with him". When Thea tries to speak to Eric, once he avoids her, Selene reassures her that she and Vivienne will help her learn how to attract the boy.
In order to help Thea, Selene provides the Harman girl with borage flowers and an Ancient Roman spell for courage, cheering Thea on once she has consumed the blossoms.
At the homecoming dance, Selene witnesses the arrival and state of Randy Marik, a boy Blaise had mentally and emotionally destroyed in the past, both she and Selene are frightened and "shocked". However, it is not known if she managed to gain blood from her date.
Vivienne and Selene are next seen at school, witnessing Blaise test her finished necklace. As with the others, she is awed by the devastating effects of Blaise's enchanted necklace, which appears limitless in its power to attract and subdue the will of human males.
Seleneis last seen at the Circle Midnight Samhain celebration, being held at her house; Thea notes the Lucna mailbox. She witnesses Blaise being taken by members of the Inner Circle, "look[ing] sober and scared" with Vivienne.
- Selene's name comes from the Greek Titan goddess of the moon, the sister of the sun Titan Helios and the Titaness of the sunrise, Eos. Selene is sometimes replaced in her function as a moon deity by the Olympian goddess Artemis. Ironically, Selene's divine namesake is famously known for falling in love with and marrying a human shepherd named Endymion, who she enchanted to sleep forever so that Endymion would always dream of Selene.
- Selene often wears colors associated with the night and the moon (black, violet, silver), in keeping with her lunar namesake. Her hair and eye color, as well as her torpid nature and use of borage (which is also known as starflower) also link back to this association.
- The plant recommended to Thea by Selene, borage, is an actual and edible plant. The "courage" the plant is said to impart in the consumer is likely due to chemicals in borage that, when eaten, cause more blood and oxygen to flow to the heart, as well as mediate hormones.
- Selene also has the same first name as the mother of Sylvia Weald.