Billie was developed in response to The WB's request for a new character, and was intended to expand the show in a new direction for a possible ninth season or a spin-off series, leading to mixed opinions of media outlets.

Christy and the demonic council known as the Triad manipulates Billie into believing the Charmed Ones are corrupted by their powers but when the truth is revealed, she eventually reconnects with the Halliwells.

When discussing the casting process, Kaley Cuoco described Billie as solely based on her physical appearance, saying: "I think they just wanted a blonde on the show.

"[2] During an interview for the ten year anniversary of the series finale, executive producer Brad Kern clarified Billie was intended to "lighten the load, screen-time wise" for the three principal actors and "bring new blood to an aging show".

[4] When describing the introduction of Christy Jenkins, played by Marnette Patterson, Kern said he wanted to end Charmed by returning to its initial focus on sisterhood.

[4] Co-executive producer James L. Conway believed Billie's identity as a novice witch added a new dynamic to the show, while Pam Shae called the character "demanding", "spunky", and "very, very confident" despite her inexperience with magic.

[17] Billie has the basic abilities of a witch, including casting spells, performing rituals, brewing potions,[18] scrying for lost people or objects using of a crystal pendant,[19] and communicating with the dead.

[17] She is shown mastering her original powers very easily and adapting them using unconventional methods, such as attaching a large quartz crystal to her computer's mouse to scry through a GPS system.

[24] Kate Ward of Bustle connected CBS's decision to revisit the supernatural drama with Cuoco's success as "one of the network's most bankable stars" for her role on the sitcom The Big Bang Theory.

[28] Bustle's Sabienna Bowman wrote the reunion should address Billie's fate following the series finale, arguing the character's future should be "more interesting than babysitting for the Halliwell brood".

[29] While Shannen Doherty and McGowan publicly supported the idea of a reunion, Dan Avery of NewNowNext.com wondered whether Cuoco had been asked to revisit her role as Billie.

[31] Billie first appears in the season eight premiere "Still Charmed & Kicking" as a college student who hunts and vanquishes demons while disguised in a black wig and a vinyl outfit.

[22] Billie later falls into an Alice's Adventures in Wonderland-themed trap set up by demons Paul Haas (Mykel Shannon Jenkins) and Black Heart (Noa Tishby), who were attempting to lure the Charmed Ones out of hiding and prove they were still alive.

[36] The Triad arranges for Billie's parents to be killed by demons (John Rosenfeld and David S. Lee), believing Christy's prolonged contact with them could sway her morality to the side of good.

The narrator of "Trickery Treat", which takes place after the eighth season, describes Billie as "[a]n above-average white witch" and the Halliwell sisters' protégée and friend.

Paige refers to Billie as the second line of defense if the sisters fail to kill the Source, and asks her to protect Darryl Morris (Dorian Gregory) and his family.

The comic book issue is about Billie's life after the ultimate battle; she moves from San Francisco to Los Angeles to finish college.

[42] In issue 16, Prue Halliwell reveals her bond to the Charmed Ones' prophecy even after death restricts her sisters from achieving their true powers, which made them vulnerable to the Triad's plot with Billie and Christy.

[49] Digital Spy's Hugh Armitage, on the other hand, viewed Billie as an example of Cousin Oliver Syndrome, a phrase referring to the addition of a younger character to improve declining ratings.

[50] Ryan Keefer of DVD Verdict was critical of the addition of the character, writing: "If it hadn't already been established that this was the last season, this event would have sealed the cancellation deal".

[48] Jon Langmead of PopMatters viewed Cuoco as unable to "generate any kind of life with her character" and found that her "awkward presence and acting call[ed] attention to the show’s weaknesses when in the past, the cast was able to distract from them".