Eon is a Chronian from the planet Concordia that hails from another Dimension. In his dimension, Eon was a warrior that defended his planet from those who seek their power. Chronians have the power to control time and access the Multiverse, and were the only beings in their Universe to exist. On one fateful day, the Chronians as a were wiped from existence by a Celestialsapien, along with their planet and Universe. Eon is the last survivor and vows to gain the abilities of a Celestialsapien to not only resurrect his Universe, but destroy the Omnipotent race.

Through his travels in the Multiverse, he discovered the Omnitrix, learning that its power to transform the user is the key to his goals. But Ben Tennyson is bound to the device in almost every timeline, so he will stop at nothing to gain the power of the watch, or even the power of Ben himself.

Eon’s age is unknown, he is essentially immortal because he constantly travels the Multiverse to transform Ben Tennyson into a Chronian and place his consciousness within him. He does this because everytime he uses his time powers, his body deteriorates.

Eon is Ben’s most dangerous enemy, even more so than Vilgax.

There is only one Eon in the entire Omniverse. Ben’s transformation of his Chronian DNA can only be unlocked when it has scanned Eon. Even if he does, Ben needs to be careful so that Eon doesn’t take over his body.

Eon only goes after Omnitrix Wielders when they have access to Alien X. He can sense multiversal changes throughout the Omniverse so he will know when a Celestialsapien is unlocked in the device. But whenever he switches, the Omnitrix shuts down forever as a fail safe, preventing Eon from transforming again.

Eon has been constantly thwarted by the time-traveling immortal known as Professor Paradox. Paradox wants to prevent Eon from having the omnipotent power of a Celestialsapien consume him and result in him destroying the entire Omniverse by accident.

Eon has body swapped with Ben so many times, at one point he even thought that he was Ben Tennyson and desired to be the only Ben in existence. He has since grown out of this insanity.

Eon is willing to mess up the timelines just to achieve his goals, and would resort to destroying all of existence if it meant that his own Universe will survive. Eon can be very intelligent and can perceive the fragility of spacetime, unlike Paradox, he fails to recognize that nigh-omnipotent power is not something that can be exploited and controlled without cataclysmic consequences.