Hijynx is the newest addition to the Decepticon side. She is Megatron's favored 'Con, but her recurring unruliness and habit of provoking dangerous beings keeps everyone on their toes.
She is primarily focused around the Transformers Prime T.V. series, where she is originally created by Megatron to defeat the Autobots (Her name was "Jynxblade"). Instead, she joins them. There, Hijynx and Bumblebee "get together" for a few episodes. Their relationship ends when Knockout and Breakdown are recruited. From then on, Hijynx stays on the Decepticon side. Her alternate mode was a regular speedy red Camaro.
Hijynx then appears in Michael Bay's "Revenge of the Fallen" as Hijynx, though seeming to have grown and matured into the stealthiest- and deadliest- soldier to ever had been in the movie. Here, she is neither Autobot nor Decepticon, and she is a cunning, flirty femme. Her demeanor changes drastically: she had become rational, and her kid-like behavior completely disappears. She once again pairs up with Bumblebee, but this time she is ever more faithful and protective. At the end of the movie, she is seen driving away into the sunset after claiming "There might be more out there for me". Hijynx's alternate mode had advanced into the 2012 Chevy Camaro ZL1.
In "Dark of the Moon", Hijynx doesn't appear until halfway into the movie, where she is battle-scarred and silent. She stays close to Bumblebee, and rarely fights back until Bee is almost murdered. After this scene, she is shown struggling near a building, holding her stomach while energon leaks through fatal wounds. Hijynx is nowhere to be found beyond this point.
In the 2014 movie, Hijynx returns, but this time she has more of her past to tell, revealing her aid to the Decepticon side, and her visions of Unicron's return.