Zaheer was the villain of the third season of the show. And my second favorite of the major villains.
Apparently a non-bender before the events of the Legend of Korra, he was part of the Red Lotus Group that wanted to kidnap Korra as a child. He escapes prison when fate decides to make him one of the new Airbenders.
He quickly reunites with his old comrades to wage war against Korra. Though, their intentions aren’t entirely evil. Zaheer doesn’t like tyrants and believes an Avatar is a tool for autocrats rather than the solution to them.
It was rather fun to see an evil Airbender. One that showed how dangerous airbending can be when used to kill, something Avatar Aang would never have done.
His love of his life was that lady that shot incredibly powerful fire magic out of her forehead. When she’s killed in the battle against the metal benders, something happens to Zaheer.
He loses all of his attachments to the Earthly world and learns how to fly like a bird instead of gliding with the wind.
His plan to kill Korra by poisoning her wasn’t just to end her life but to end the existence of the Avatar itself. Knowing that the poison would trigger the Avatar state, had he bet correctly, he would have won. But because she went into the Avatar State, she was able to break free and survive, thanks to her friends getting the poison out of her body.
We see him again next season as a prisoner. Ironically Korra has to ask him for help. And surprisingly he agrees mainly because the new villain Kuvira was a tyrant second only to Fire Lord Ozai in corruption. Which he gladly offers his services to help stop her. Very unexpected.