Eon's Backstory

16 years ago, Kyukon (working name) realized she was out of time. The first Ninetales’ thousand year lifespan led her to procrastinate recording what she had learned, meaning that incredible amounts of arcane knowledge were about to be lost. It didn’t help that humans were constantly chasing her, either.
A couple men claiming to be from the “Plasmid Foundation” somehow found her home late at night in the US and tried to get her to volunteer for some… experiments. When she told them to get lost, they attacked. Sixty years ago she would have incinerated them in a heartbeat, but at this point she had finally grown old and frail.
Not frail enough to soar over their heads and sprint away, though. The men chased after her with their Aura-powered body suits, jeering that if she died on the run her body would still be worth plenty to Dr. Jarred. She used every wile and trick she knew to avoid their detection, but they always managed to find her.
Nevertheless, she knew she was but hours from death. She had enough strength for one last spell, but that was all. Kyukon knew exactly what spell that would be.
But first, a suitable host. She felt carefully for any signs of Ninetales Aura, but as could be expected there was none in this section of the world. Fire Aura? Still nothing. Hybrid Aura at all…? How could there be only humans in this stinking place?
A bullet caught her in the arm, tearing through her decrepit body. She stifled a yelp and slipped away into the nearby trees. She ran on silent paws, trying to put as much distance between herself and those humans as possible. A short time later she found herself in a human neighborhood which was… devoid of all hybrids, unfortunately. Blood leaking into her palm reminded her that time was short. Jumping between houses, she searched the windows with her vulpine night vision until she at last found a suitable host.
Suitable, but definitely not her first choice as one. The human infant through the window slept soundly in his crib, blissfully unaware of the chase just outside his home. Kyukon hesitated, but a sharp stab of pain from her bleeding arm reminded her she was totally out of time.
With her power she unlocked the window from the outside, gently sliding it open as to not wake the babe. Once inside, she gently placed her clean hand on his forehead and started to chant softly. The child stirred, but did not awake.
For several minutes Kyukon chanted, transferring crucial pieces of her Aura into the child, ensuring all of it was locked away far outside of his awareness. Piece by piece she copied her thousand years of knowledge, and for once in two decades she felt relaxed, secure in the fact that her wisdom would live on.
And finally, a curse. She let her tails gently touch the infant’s forehead, giving her full access to weave reality itself around him. The most powerful curse she had ever wrought took hold that night, setting events in motion that would persist for years and end with this child meeting another Ninetales and becoming one himself.
Her legacy would continue. With a smug grin she leapt outside, closed the window, and jumped down to the streets below where those humans were waiting. With the rest of her power, she converted her body into Fire Aura, setting herself ablaze… no. Turning her into fire itself. She laughed maniacally as she brought her own life to an end, having finally completed her life’s work. She would die today, but her powers would live on in that soon-to-be-hybrid human, and when his lifetime expired he would pass it on that knowledge to his successor, and so on for all eternity.
What was that Latin phrase she loved so much? She remembered now. Infinite Progression of Fire: Ignem Progressionis Infinitum.

Excuse the quality of writing. Basically, Eon has his name because he possesses an eon of knowledge within him, which also explains why he has Drought and such intuitive Hypnosis. But he doesn't just have everything: Kyukon (still looking for a better name) sealed away almost all of her knowledge behind "Aura gates", mental locks that Eon can only open if he has enough power or control of his Aura. If he has too much power, the gate unlocks to teach him control of that power. If he's demonstrated great control over the power he does have, the gate unlocks to grant him more use of that power.
This knowledge takes the form of a hallway or series of rooms. Each room contains a few scrolls each containing only a Japanese kanji symbol that upon being viewed instantly fills Eon's conscious mind with knowledge on the topic given by the kanji, even if Eon can't actually read it.
Also, a projection of Kyukon lives there, a remnant of her Aura that explains to him what the library is and how to unlock it. She also explains that there are so many gates that takes so much more power that she'd be surprised if Eon unlocked them all within 500 years. I'm planning on making her a sly fox that likes to mess with Eon, something that conveys why she was the origin of the myth of the kitsune (because of course she was).
Finally, no more true immortality for him. It's just not important or worthwhile.

As it stands, I'll have Eon desperate the days leading up to the competition. With all his training he can barely hold his own against his teammates and other sparring partners, and as he wracks his brain for some way to succeed, he hears a voice in his mind: "Well, I guess I had to show you some day." Eon is then taken within his mind to Kyukon's library, where he's given a chance to open the first gate. He fails at first, but during the climactic battle between him and Sidi (the Umbreon captain of Unseen Powers), he finally manages to open the first gate, and behind it is just enough strength for him to secure victory.