Jarrah is an arachnid sorceress who serves as one of the main antagonists in the first season and as a minor antagonist in the second.
Spider Queen Jarrah is regarded by many characters as a formidable force because of her expertise in Nightcasting. She is cunning and witty, and does not appreciate being looked down on. She takes great confidence in her power, and that is indeed justified because she is capable of much. She is also considered to be treacherous (Season 1 Episode 1 Scorpion Soldier who questioned Marmoo). She can also be quite sadistic.
She allies with Lord Marmoo in the first season to help Marmoo pierce the Veil that protected the Amphibilands. It was made by King Sergu the turtle king and powerful Dreamcaster, who also had been Jarrah's teacher in the past but she deviated from his teachings believing Sergu was hiding knowledge from her. The reason she allied with Marmoo was because she believed attacking the Frogs would draw out Sergu to vulnerability.
In order to take down the Veil, she had to use pieces of the day it was formed. She asked the Scorpions to bring back dirt. She then was able to let a small number of scorpions through in order to get the High Wattleflower, which would allow her to take down the whole veil. She goes to Marmoo's headquarters, expecting to be given a whole tree, and is also later promised a snack (Gee). Jarrah is instead given disappointment in the form of an escaped snack and just a mere flower from the tree. Though she does remark the place lit aflame and Marmoo in distress makes for an amusing dinner show.
She took quite a while to bring the veil down, though she was able to break down a sliver in the beginning, which permitted the Scorpion Army to funnel in. After the battle she brings Marmoo back to life stronger. Though kept him under control to a degree by holding off completing the spell. Marmoo was vulnerable with a soft carapace, and intended to use him as a weapon to fight against the frogs and her true opponent the Rainbow Serpent. She's shown to take Lady Falgha as a student in this part of the season.
Jarrah seeks to stop the frogs from receiving a message from the Rainbow Serpent, sending Ghost Bats after the Platypus and their Stargazer. She also sets out to destroy the frogs and stop them from meeting the serpent. She is too late however, and Darel is able to have a brief interaction with the serpent. She threatens Darel to tell her what he was told. She is not told anything of worth. She is then frozen by a melted avalanche done by Yabber. Falgha melts her later. She comes back to life, enraged and out for blood, in that moment of anger, she hardens Lord Marmoo's carapace despite Falgha's hesitance. Swiftly then she is murdered by Marmoo.
In the second season she's dead but still a threat because of how she can influence Koa. She can possess him and use him to use his powers for evil. She fights with Sergu and Koa for control over the body and power, but is expelled alongside with Sergu. She's seemingly gone for the time being, or hopefully forever.