Reborn - Episode 64 "The Truth About Anger"

After the fight, Xanxus is released with the power of the 7 rings which he was originally released by from the 9th.

There is a short flashback of his life, and a secret is revealed: Xanxus is not actually the 9th's blood son, and so, the rings rejected him. At the end of this, an elite group of Varia arrives.