She journeyed to Earth shortly before the episode "Mad Dogs and Aliens" and broke Dr. Drakken out of prison after an intercepted broadcast of his earlier performance on American Starmaker. This broadcast lead her to believe that Drakken was "The Great Blue One": a legendary figure from her planet's mythology who, it was prophesied, would lead her people to conquer the universe; a leader to whom she would pledge her allegiance and her arsenal of advanced weaponry. With no other point of reference to work from, she comes to this conclusion through the part of the prophecy that stated the Great Blue would contact her people from "beyond the stars".
Excited at the prospect of being able to access advanced Lorwardian technology, Drakken agrees to join forces with Warmonga. The alien proves too much for either Kim or Shego to handle alone; however, working together, they manage to gain the upper hand.
She eventually leaves Earth after Wade and Jim and Tim fabricated a new "Great Blue One" out of their school mascot costume and convince her that Drakken is not the person that she has been looking for.
She reappears later on in the 2-part final episode "Graduation". She returned with her battlemate Warhok, commanding an invasion force to conquer the seemingly primitive Earth. Warmonga is finally defeated when Ron Stoppable manages to tap into his dormant Mystical Monkey Powers and defeat her and Warhok in single combat, throwing them headlong into their crashing spacecraft just before it explodes. She can be heard screaming "Frackle!"
Warmonga is extremely strong, a fierce fighter, and is very eager-to-please, though she can be very literal-minded when following orders.
Her personality has yet to be explored in depth. What is known for now is that she exhibits an incredible obsession with finding the Great Blue and pledging her loyalty to him (whomever the Great Blue may be), and that she is somewhat gullible. Although, based on her behavior when she believed Drakken was the Great Blue, she seems to treat those she respects with great kindness and an undying loyalty, making it difficult to truly regard her as evil.
Still, communication with Warmonga has proven to be taxing at times. Despite her minor traits of always referring to herself in the third person, as well as yelling out her name as a war cry (it's unclear as of yet if this is simply her behavior or if this is typical of her entire race), Warmonga has absolutely no concept of Earth slang phrases. When Drakken tries to explain to her the concept of "showing someone the door", she actually picked Shego up and tossed her through the door. This leads to another problem. Being every bit as powerful as her enormous size indicates, Warmonga has little understanding of her own strength in comparison to regular humans. This can make her dangerous even when she's trying to be nice. More than once, she found herself hugging Drakken and nearly crushed him.
In "Graduation" she appears to be as malicious as Warhok. When Warhok told her they're going to take Kim back to their planet and mounted her on Warmonga's wall as her own trophy, she just smiles while looking at an unconscious Kim being held upside down by the leg. She is gleeful to have her dead and stuffed, and she's completely aware she's only a child (at 18).