Zuko tossed and turned in his bed all night, unable to relax even thought he was tired after two long days of work. He would have to meet with the Kyoshi Warriors in a few hours, but he could not sleep. Not when his sister wasn't next to him. Not when she on the other side of the country, about to surround herself with people that would try to kill her if they found out about her plan.
He had spent nearly an entire day waiting for the hawk to arrive with her message, and was the first to read the letter. He had to do it a second time because his brain ignored everything other than the words 'We're safe'. He made sure to follow Azula's detailed instructions very carefully, properly preparing for combat and starting to choose who would follow him into battle - even though said battle wasn't upon they just yet. Azula already had a rough estimative of how many enemies they'd be facing now that she had actually gotten the traitors to talk, and from what she had gathered, their number was just a bit smaller than the nation's official army, and was likely to be defeated since they'd also have to face their foreign allies.
Still, they're weren't sure how skilled the insurgents were, and since someone as powerful as Ukano was supporting them, there was no telling who else had been willing to do so. Proper armors and weapons combined with skill and strength could be enough to even the odds, or maybe even to win. His paranoia was consuming him, and he did not sleep even after doing literally he everything he could to speed things up while still properly preparing for conflict, and now he was about to face another sleepless night.
Zuko got up again for the hundredth time, analyzing the letter, paying attention to every word, as if the answers to his questions about just how safe his sister really was would simply appear on the paper and assure him he didn't have to worry. Eventually he put it down, and went back to bed, trying to get at a least a little sleep, even if for a few minutes.
But was impossible for him. He had gotten too used to sleeping with Azula. The bed seemed bigger and felt cold, and his sister sweet perfume was still in it. He missed her warmth, holding her close, kissing her all over, making love to her, hearing her heart beating... he even missed her rolling her eyes and complaining that he was too clingy and too emotional - especially because she'd always let him do it anyway.
And even though he wasn't as afraid of telling people about their relationship as he had been before, he still wanted her to be there by side when he told Suki, Ty Lee, and, later on, Sokka.
He couldn't say why he was feeling more confident this time. Maybe it was because he had managed to convince all the other important people in his life that this wasn't as bad as they were assuming, maybe he was just too worried about Azula's safety to even think about anything else, or maybe his sister blind faith in him and constant reassurance that everything would be okay had finally given him some peace of mind - on that matter at least.
He immediately thought of when they told their mother about their engagement. He remembered how happy the two of them were, how affectionate Azula had been, how they first said they loved each other...
Stop being so dramatic and do something useful, he could almost hear her berating him.
Zuko sighed and did what 'Azula' told him to, taking a bath, dressing up, and going to their office to start working on his regular duties as Fire Lord before the sun came up. He couldn't do anything about his sister insane plan, but he could at least keep ruling the palace and their nation as best as he could so he'd be able to fully concentrate on helping her once she told him it was time to attack all the traitors.
I'll take care of you, Azula. In whatever way I can.