Amon's Story

Speculation of Amon's identity (apologies if my theories seem crazy):

• Lee, the little boy on the farm that Zuko stayed with in ATLA episode, "Zuko Alone". So, that would make Amon about 70+ years old, which is somewhat plausible if he was as bamf as Iroh was.
• Bumi, Aang's son. When Tenzin said that spirit-bending was impossible, he sounded like he knew someone who could spirit-bend but kept as a secret from Korra. Perhaps Aang taught his sons how to spirit-bend theoretically but none of them could master it till now. But this also means that Amon's story was a lie.
• Ozai, assuming he found a way to spirit-bend after learning from experiencing it firsthand. He would also have to find a way to live forever. Perhaps he found the elixir of life/philosopher's stone/etc. etc.
• Jet - harboured intense hatred for firebenders.
• a new character. Very likely.
• someone who had his face stolen by Koh, the face-stealer. LOL.