The first time Gaara thanked Temari was when they were on the way back to Suna after the failed Konoha invasion. After a few hours of travelling to try and get as much distance from Konoha as possible, the siblings stopped for the night in a small clearing in the forest. Kankuro had set up several traps around their campsite and then fell asleep right away, as he had not fully recovered from his battle with Shino. Gaara was sitting on the grass, propped up on a tree trunk. Temari was tending to his wounded shoulder, first wiping of the blood and putting ointment. She thanked the stars for the many years she has trained as a shinobi as it kept her hands from shaking despite the series of events that have led up to their current situation. She then proceeded to bandaging her brother's shoulder while she thought of how to get food for the night. Whatever food pills they have wouldn't suffice; normally, she would berate Kankuro for falling asleep and neglecting his share of responsibilities, but she understood that his fight with 'that weird bug freak', as Kankuro had put it, took its toll on his body, so she let him rest. She would just have to see if there was a stream nearby so she could catch a few fish. She also wondered where in the world Baki was; prior to arriving in Konoha, he had told the siblings that if ever things wouldn't go as planned, he would meet up with them for further instructions. Temari sighed. They would just have to wait until Baki finds them. Temari began to clean the dried blood on Gaara's forehead while thinking about what their plan of action would be if they were ambushed by shinobi from Konoha during the night to capture them and take them back for interrogation; or what she and Kankuro would do if Gaara had another one of his 'episodes', which she thought was highly unlikely given his condition, but she could never be too sure...
"Thank you."
Temari had been so lost in her own thoughts that she did it took her a few seconds to realize that her brother had said something.
"Err... D-did you say something, Gaara?"
"I said thank you. For treating my wounds."
Temari raised her eyebrows in surprise. "O-oh! Sure, no problem." She dabbed a small amount of ointment on the small wound on Gaara's forehead. "I'll change your bandages again tomorrow." With that, she stood up and returned the roll of bandages and jar of ointment to one of her pouches, realizing that that was the most she had ever said to Gaara, as far as she could remember. Moreover, that was the first time he had thanked her-and said anything polite to her, for that matter.
Later that night, as Temari began to make a fire to cook the fish she caught in a stream which was fortunately near their camp site, she began to think about the thank you she received from her brother. She was a highly analytical person, but she found no reason as to why Gaara would say that. Had his fight with the Uzumaki kid from Konoha have something to do with it? Temari wasn't too sure. She would just have to talk about it with Kankuro when they get home. She wasn't about to let down her guard, either. Kind words spoken from the person she feared most and had terrorized her for most of her life wasn't going to change her mind that easily. She knew it was harsh given that they were siblings, but right now, she just wasn't convinced, and Gaara had told her and Kankuro more than once that he never even considered them as his siblings. Later that night, however, as she lied down on the grass to rest, she kept replaying the moment where Gaara had thanked her. She didn't want to admit it, but somewhere deep in her heart, a hope for her brother had sparked.