Kennedy is introduced as a "potential Slayer": one of many girls who might become endowed with supernatural abilities, destined to battle evil creatures such as vampires and demons, like protagonist Buffy Summers.

In the episode "Get It Done", she gains first-hand understanding when Willow drains a significant portion of her life force in order to reopen a portal for Buffy.

Kennedy becomes one of the more prominent Potentials, overseeing their training in "Get It Done", and giving them orders in "End of Days" while Buffy is absent and Faith is incapacitated.

In the issue "Anywhere but Here", a flashback recounts a conversation that reveals that Kennedy is worried that Willow keeps her away from Buffy's inner circle because she is ashamed of her.

Over the course of the series, Willow remains distant from Kennedy, in part because she is having a sexual relationship with her magical mentor, the demon Aluwyn.

In its aftermath, after Buffy's actions have brought about the end of magic, Kennedy is dumped by Willow, who is in turmoil as a result of the loss of her powers and her connection to Aluwyn.

Buffy joins Kennedy's organization, and before long it becomes apparent that their client—a social network founder and Internet billionaire—is on the run from the demonic law firm Wolfram & Hart, who funded his website's development and plan to use it to return from their extra-dimensional exile.

Kennedy next appears on a recurring basis in the second volume of Angel & Faith (2014–), as well as in crossover scenes in the first two issues of Buffy Season Ten.

As Faith is about to quit, however, Kennedy offers her a mission to find Riley Finn, who has gone missing in South America.