zk antis wouldn& #39;t admit this but in the last fight it HAD to be katara beside zuko for not just logistical but also for symbolic reasons which aren& #39;t as simple as ~he is fire she is water~
In each finale it was always specifically Zuko and katara against each other except the last when they were together on the same side. Zuko taking the lightning bolt is the flip side to Zuko specifically betraying katara in ba sing se after their bonding in the catacomb