This image has surfaced the internet directly from Comic Con 2014 thanks to avatar-mom. It appears to be a younger Suyin & Zaheer in the circus.
In Book 3 episode 3 The Metal Clan, Suyin mentioned that she joined the Circus. Here is a quote taken from the episode:
When I was sixteen, I left home to explore the world. I sailed the seas on a pirate ship, joined a traveling circus for a while, and lived in a sandbender commune in a desert.
Coincidentally, screenshots show that Avatar will be travelling to the Misty Palms Oasis (which is in the desert) and other desert locations in a future episode(s). Zaheer and Suyin in the Circus together, Suyin stating that she used to live in the desert & Team Avatar travelling to the desert as a relevant part to the plot. Could this all be somewhat linked?
This part isn’t really relevant to the rest of the post, but: It should be noted that the official Book 3 trailer hints at their desert trip being a defeat for Korra as you can see in these two screenshots [ X & X ] that Korra & Asami are escaping the desert and Korra is collapsed into Asami’s arms.