When they were young, Kankurou treated Gaara like a little kid.
The little kid looked so fragile, so afraid; Kankurou was scared he might crack with the slightest touch.
But he proved to be much tougher in a battle than him, and Kankurou didn't like that.
Kankurou wanted to be an older brother- to be able to protect his frail little brother, but when he had that ultimate sand defence, Gaara wasn't giving him a chance.
When they grew slightly older, Kankurou treated Gaara like a monster.
The monster looked so uncaring, so ruthless; Kankurou was scared that he might do something even worse without his guidance.
But he proved to be much, much tougher to reprimand- Kankurou didn't like that.
Kankurou wanted to be an older brother- to be able to keep his ruthless little brother in line, but when he looked threateningly at him, Gaara wasn't giving him a chance.
When they reached higher levels, Kankurou treated Gaara like he always wanted to treat Gaara.
Look at him, with that Kazekage outfit- so proud, so commanding; Kankurou was proud as well- Gaara's going to do just fine without him.
But he proved to be different that expected; especially when he asked specifically for his assistance.
Kankurou finally got to be an older brother- even though Gaara was not feeble enough to be protected, or unfeeling enough to be advised, he gave Kankurou a chance just to be there for him.
And that was enough.