They both left their homes at age fourteen to follow the Avatar, and they've both made him the center of their lives, physically and spiritually.

YES! That's almost the same thought, I expressed on another forum a little while back, as one of my reactions to the NYCC trailer. The episode that really highlights these parallels is The Storm. Actually, if I ever shipped romantic Zuko/Katara, this would have been one of my starting points.

On the platonic level, I really love that Zuko has some connecting points with all the members of the gaang, which makes his bonding time with them so good, once the preliminary problems are overcome.