In A Void Dance, she, along with Commander Korasi, is sent with the player to investigate and find the escaped pest, which turns out to be a Void leech. Korasi holds a grudge against her but eventually they make friends, and, at the end of the quest, Jessika is offered a chance to join the Void Knights.
Jessika seems to have a very slanted view of the pests, and believes them to be intelligent, kind-hearted creatures who are controlled by a "Hive-mind" which orders them to attack Gielinor. This view is probably true, however, since the dialogue with the Void leech at the end of A Void Dance seems to confirm it. After The Void Stares Back, Valluta refers to the Pest Queen as the "slave-driver of pests", further confirming this view and indicating that the Pest Queen is the hive-mind; although the player kills a pest queen during the quest, Valluta mentions that a new one will hatch afterwards.
In The Void Stares Back, Jessika is one of the NPCs that accompany the player once the player has unlocked the Black Knights' security rooms. It turns out that 'Professor Melville' had deceived her and others and was actually Wizard Grayzag, who is planning to summon the Pest queen and wreak havoc with her. The player is forced to choose whether Jessika or Korasi will be saved. Whichever one the player chooses to save will explode the foodgoo in order to close the Void Portal, while the other will die immediately at the hands of Grayzag. After the quest Commandant Tyr mentions that she is now battling against the void with the void knights.
Jessika stuck in Limbo.
Jessika also features in Nomad's Elegy, depending on the player's choice in the Void Stares Back. If the player choose to let her die, then she is one of the four adventurers aiding Death, Icthlarin, and the player. However, if the player chose to let her live and let Korasi die, then she is a memory of Korasi's encountered in Limbo.
During the non-canonical Gower Quest, Jessika appears in Behind the Scenes if she was killed in The Void Stares Back (if she survived then Korasi appears instead). If Nomad's Elegy is completed, she explains that she is the NPC of the "living" version of Jessika, as opposed to the one encountered in the Underworld.
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Cut content during Nomad's Elegy revealed that she had a relationship with Korasi. If she was killed, she was supposed to have written a letter to Korasi. This was removed due to time constraints.[1] Korasi's version of the letter also revealed that Jessika was promoted to commander in the Void Knight order, after The Void Stares Back.