Valkyrie Cain's reflection is the main reflection appearing in the series. It was created in the first book by Skulduggery so Valkyrie could go on adventures and not be missed by her parents. When Valkyrie is ready to relive the memories, the Reflection will step back into the mirror and say "Are you ready to resume your life?" It was also known to have even developed human feelings.
This is the first we hear of the reflection. It is created by drawing a symbol of an eye in a circle with a wavy line through it. Skulduggery then said the spell words "Surface speak, surface feel, surface think, surface real." Valkyrie (then Stephanie Edgley) touched the mirror and the reflection stepped out, scaring Stephanie in the process.
The reflection plays a bigger role in this book. Near the beginning, the reflection is attacked by Dusk and two of his Infected. In the middle, the Torment forces Skulduggery to kill Valkyrie in exchange for the location of the Grotesquery. The two ask for a minute alone, in which they summon the reflection using the same symbol and spell with a puddle. Skulduggery then shoots the reflection and gets the information. When Valkyrie returns the reflection to the mirror and touches the surface, she relives what it is like to be shot.
In this book, glitches from being shot and overuse are beginning to shown, such as sighing. When Valkyrie is in conversation with the reflection, Melissa nearly catches it. The reflection receives Valkyrie's first kiss. The kiss is with Gary Price, a boy in Valkyrie's school. When Valkyrie re-lives the memory, she doesn't feel any emotions.
Later on in the book, the reflection is staying with the Edgley's as Valkyrie's parents are in Paris. Tanith pays Beryl a visit, asking for the reflection. Valkyrie hasn't answered her phone as she had been arrested by Remus Crux. Beryl is taken back by Tanith's appearance in her leather.
At the end of the book, Valkyrie is consumed with sadness by Skulduggery's departure into the dimension with the Faceless Ones. When her parents return from France, Valkyrie relives the memories from the reflection.
In this book, the Reflection plays a bigger part. When Valkyrie is preparing to have her True Name sealed, the Reflection has another glitch by saying "our parents" when referring to Valkyrie's parents. While Valkyrie was having her True Name sealed, she hallucinates and the Reflection appears. It encourages Skulduggery to shoot Valkyrie, and says that it can take Valkyrie's place as she does not have Magic, and won't become Darquesse.
After the Remnant outbreak, the reflection touches on Valkyrie's reasons for not telling Skulduggery she's Darquesse straight away. It says she didn't tell him as she's afraid of him. Valkyrie ordered it to go to bed but it didn't go straight away, which are other glitches; talking back and disobeying commands. Valkyrie comments on how, even though she doesn't want to listen to the reflection, it's speaking the truth.
In Death Bringer the reflection is thought to be Tanith or another intruder in Valkyrie's house and Alison starts crying. The reflection was wandering out of the mirror because Valkyrie hadn't touched it, and there was still some homework for it to do. Valkyrie accuses it of lying, but it was telling the truth. She then goes back downstairs and sees it downstairs, holding Alison who has stopped crying because she thought it was Valkyrie.
Throughout the book the reflection becomes more and more independent as it suggests its own ideas and personalities, although it continues to show it is a part of Valkyrie when she says that Dexter Vex is good-looking, to which she responds to Valkyrie's protest by saying, "My opinion is your opinion." It travels to the Alternate Dimension accidentally with Valkyrie, but is captured & tortured. It claims to still be loyal to Valkyrie.
At the end the reflection murders Carol Edgley, takes possession of the Sceptre of the Ancients in an attempt to have "Stephanie's" life and kill Valkyrie, Skulduggery and all of their friends. It also creates Carol's reflection and tells it that it could become independent like itself.
She shows to behave normally, until a moment when she turns on Valkyrie with the Sceptre and attacks her. She breaks the mirror so she can't return to a reflection, and when Valkyrie acknowledges her name is Stephanie, she evolves enough to become a "her", or a living person. She helps Skulduggery fight the Warlocks and using the Sceptre, kills many of them, including Charivari. After, she stays with her family as Valkyrie is consumed by Darquesse and may attempt to kill them.
Stephanie helps Skulduggery track down the remaining renegade sorcerers and, somewhat unwillingly, assists in Valkyrie's return. Stephanie is later attacked by Darquesse, who is possessing the body of Obloquy. Darquesse beats Stephanie to death and uses her body as a vessel, after marinating it in a magical fountain in the Caves of the Void.