In the Season 3 episode "Obsession," Alicia is among the group of Smallville High School students on a field trip to LuthorCorp. She gets trapped in a malfunctioning elevator with Clark Kent, who's forced to use his powers in front of her to stop the elevator. To prevent Clark's secret from being exposed, she reveals her own power of teleportation and teleports herself and Clark out of the elevator. She promises to keep Clark's secret.
Clark and Alicia start to bond, and they slowly form a romance. However, Alicia becomes possessive of Clark to the point where she attacks her own father after he warns Clark about his daughter and later attempts to kill Lana Lang, only for Clark to stop her by dousing her in lead paint.
Alicia next appears in the Season 4 episode "Unsafe." She is released from Belle Reve with a clean bill of mental health, and returns to Smallville, where she rekindles her relationship with Clark, who's initially wary of her. When her therapist, Dr. William McBride, stalks her and insists that she not see Clark, Alicia tries to persuade Clark to leave Smallville with her. When Clark refuses, she gives him a Red Kryptonite necklace, causing his uninhibited personality, Kal, to emerge. Kal and Alicia head to Las Vegas to get married so they can consummate their relationship, but during the honeymoon, Alicia decides she wants "all of Clark" and removes the necklace, restoring Clark to normal. Clark, however, is disgusted with Alicia's actions and leaves.
Later, when Clark is confronted by Dr. McBride at gunpoint in his barn, Alicia appears and teleports in front of Clark, taking a bullet fired by Dr. McBride at Clark, protecting Clark's secret and redeeming herself in Clark's eyes. Sometime after that, Clark visits Alicia in the hospital and returns her lead bracelet (which prevented her from using her powers). In the final scene, Alicia comes by the Kent barn, where she and Clark reconcile, and she breaks down in tears as Clark hugs her comfortingly.
In the next episode, "Pariah," Alicia becomes the prime suspect after Lana and her boyfriend Jason Teague are attacked in a locked room. When Clark begins questioning her innocence, she tricks Clark into revealing his powers in front of Chloe Sullivan. Tragically, Alicia is murdered by Tim Westcott, a metahuman who turns out to be the one who attacked Lana and Jason earlier in an attempt to frame Alicia.
Alicia is buried in Smallville's cemetery.
According to the High School Yearbook, Alicia was most likely to "Travel the world".