What is the ruling on deducting the amount of a SAHER traffic fine, which the brother did not pay, from the car rental fee, given that he refuses to pay it and threatens to supplicate against his sister who paid the fine?

If a traffic fine is due to the driver's actions, such as speeding, the original principle is that the driver should bear it. If your brother delays in paying it, you are allowed to take your right from his money without his knowledge. We advise you to be keen on maintaining a clear relationship with your brother. If you find a way to appease him while keeping the money, then do so. Otherwise, give him the money and continue to demand your right from him. And if you consider your fine as a charitable act and intend by it to maintain family ties and give charity, your reward will be greater.