Nine million years ago, she was a civilian robot called Ariel romantically linked with dockworker Orion Pax. When the Aerialbots were transported back in time, they met Orion Pax, Ariel, and their friend Dion. As Elita-1, she is romantically linked to Optimus Prime, the upgraded form of Orion Pax.
When Megatron attacked the energy storage hangar where Orion worked, he fatally wounded both Ariel and Pax.
The Aerialbots took Orion Pax to Alpha Trion, who reconstructed both Pax and Ariel. Both became important commanders of the Autobots, Optimus Prime and Elita-1. They remained romantically linked after their reconfiguration.
Four million years ago Elita-1 parted ways with Optimus Prime as he lead his ship the Ark on a mission to gather energon. She wanted to come with him but Optimus insisted it was too dangerous. Optimus vowed to return for Elita, but caught in an explosion, Optimus believed Elita-1 to be destroyed.
Elita-1 is the female Autobot commander on Cybertron trying to liberate the planet from the corrupt grip of the Decepticon guardian of Cybertron, Shockwave. Advised by Alpha Trion, she led a group of female Autobot resistance fighters including Chromia, Firestar, and Moonracer.
Elita-1 is captured and used as bait by Shockwave to lure Optimus Prime into a deadly trap. As Shockwave predicted, Optimus Prime traveled back to Cybertron to uphold his promise and save his love.
Elita-1 possesses a rare and powerful weapon built within herself that can temporarily halt the flow of time within its radius of effect. However, the weapon drains her life force, so she only uses it when there is no other hope of victory. When used, one of the few things that can save her life is a power transfer from Optimus Prime, who has a compatible power system to hers.
Elita-1 only appears in one episode (The Search for Alpha Trion). Her story as Ariel is told, along with Optimus Prime's [as Orion Pax] in War Dawn. As the newly-built Optimus Prime leaves to fight Megatron with the Aerialbots, Alpha Trion hints that he will rebuild Ariel as Elita-1. She never re-appears afterwards, and many fans presume she was killed when the Decepticons conquered Cybertron between the second season and the movie.