Ninjago the forgotten Phoenix (A Kai fan fiction)

As Ninjago settles into peace, not all is what it seems. The ninja came back from a quest to find that Kai hasn't been himself. While telling Sensi about their friend's odd behavior, Sensi knows that these are the minor symptoms of a powerful Phoenix awaking inside.
But others might be envious of his new obtained power so when evil threatens to take it, Kai is now in the secure protection of his friends, and a stranger. Who is this stranger and what does he specifically want with Kai?

Will Kai be able to control his newly, or maybe not so new power?