Parenting roles

It is funny when your children know what your going to do when other is in trouble.
This afternoon Brendan and Carter was outside playing with the neighbors. Carter is to stay with Brendan. Come on he is only 4, Brendan being 10 we have told him that it is fine to just watch him and we check on them about every 10 minutes to make sure we can see them. They can't be out of site from us looking out though either. Well they asked if they could go over to the park and I told them yes but that was it. To stay with each other, don't talk to strangers etc...
About 15 minutes later Carter came in crying said Brendan hurt his feeling.(That is Carter favorite saying to anything Brendan tries to do or say to Carter and he doesn't like it) I asked how and he said Brendan said I was ground from riding the scooter. I asked why? He said Brendan kept yelling at him to wait. Then in walks Brendan mad. I told him to calm down and he tells me Carter took off and wouldn't wait on him. That he keep yelling for him to wait but he wouldn't and then that he can't ride the scooter anymore cause he wasn't following directions. Then Carter pops off and said you wasn't being nice. You didn't say please. How can you argue with that. He was right. I told Brendan you could have been a little nicer and not so bossy and explained to Carter that Brendan will get in trouble if he didn't stay with him and that he should have listened whether he was being nice or not. There of course was more arguing between the 2 of them and then I had to say just stay in if your not going to be nice to each other. That changed their tune really fast and with the door bell ringing and Gabriel S. out side waiting off the 2 went to play some more in the parking lot across the street at the park. One riding the razor scooter and other on the rip-stick skateboard.