Zuko might as well be chained to the palace, but Katara comes and goes as she pleases. At a moment's notice she's gone to visit a village or see to a clinic. Zuko wouldn't even know when she is in the palace, but that he is always finding her – not in the halls or the meeting chambers but in the courtyards. Like Zuko, Katara prefers solitude and quiet when she can get it, and they find themselves haunting the same forgotten gardens.
It's like a secret. They never speak of it. In fact, they never speak. For all that they used to fight each other, fiercely, during the war, now Zuko feels almost timid when they find themselves alone. She must feel something similar, because she allows the silence to rest peaceful between them.
Zuko realizes that Katara must be past eighteen now. Her wide blue eyes seem to hold every ocean she's crossed. Every time their gazes meet, Zuko sees the ocean in her eyes and he feels as though he's made of nothing but cinders and ash.