Was he with Tenzin? Or did he slip away at some point? Tarlokk wasn't the one to come to the statue searching for Korra, Tenzin was. Wonder where he sneaked off to, he was suppose to have people ready to protect Korra from Amon after all.

Let's look at some tidbits...

Amon: So the Avatar has arrived in Republic City early, looks like we'll have to accelerate our plans

How would Amon have such knowledge of her being early? Unless of course, Tenzin mentioned to the Council his plans to prolong Korra's training.

In Amon's fake story, he makes a relation to Zuko when saying he was scarred. Just like when Tenzin called him out on relating himself to Aang. Dude must have an ego trip and think he is as great as both heroes that made the city.

Then there was his persistence was Korra. He needs Korra on his task force in order to get nonbenders pissed with Korra. He didn't take her bending away yet because he must first ruin her reputation.

All the pieces of the puzzle fit.

I have a couple theorys of who Amon could be though they are a little crazy.

1. Amon is an air bender, but not of Aang's descent. His grandparent's left the Air Temples not long before the Fire Kingdom attacked. They had to stay hidden all their lives and couldn't bend. His grandparents had air bender kids and they were taught all their lives that bending was bad to use and only use it if your life was in danger. They were still taught the techniques of air bending and mastered it. Then this kid had Amon who was also a Air bender and taught that bending was wrong to do in public cause that was what one of their parents had been taught about bending being bad and thats how they thought things worked. There is also the possibility that fire rebels found the family when Amon was young and found out they were air benders and killed his parents since they were Air benders letting Amon live cause they couldn't kill a child. So Amon was taught how to use Air bending and is also a master of it. The main thing that made me think of this is that when he is fighting Lightning Bolt Zolt he dodges quite swiftly the attacks instead of blocking much like an air bender. Air benders main way of fighting is dodging and fleeing which is what he does, while most other benders use their bending to block an attack which is the way he would have been use to doing if he was any other kind of bender. So I think he is an air bender that has been taught not to use bending and its wrong to use so he is now changing the world into the way he thinks it is suppose to be.

This would somewhat make sense for them to do cause it would be interesting to see air benders in a different way other then just good people. We have seen all other benders in not playing the good role. I don't think he will be a fire bender cause they have already been the evil ones and I think the creators will give them a break. I think Tarrlok is going to be the bad water bender so I doubt they will have to bad water benders. I don't think it will be an earth bender but I really dont have a reason for that

2. This one is my crazy idea but I think Amon could also be admiral Zhao from the first series. I know he was suppose to have been killed but we never really saw him die just dragged under water. I think he might have been taken into the spirit world even though neither Aang nor the fish were from the spirit world but I think something might have caused him to go there. He might have returned now back from there and learned how to block bending while in the spirit world. Time might flow differently in the spirit world so he might not have aged at all. So now he is back mad that the fire nation is no longer what it was and wants to bring vengeance to all benders, the benders that beat the fire nation and fire benders for giving up on the war. This would explain him covering his face cause that would show who he is cause he is a famous person in the avatar world.

3. His story is true and he is just a nonbender that learned a way to block bending.

I'll laugh when it's Tarlokk.