Why? The Frog Was Disturbed

Rila's job was to protect Ban. Brando clearly have some murderous thoughts towards him and she would not let this one slide. Even if it means falling out with Yakob who was clearly stronger than her, she would not mind it as she and Ban can just escape after getting rid of Brando. 

Brando was pretty bewildered at this moment again. The Homewrecker Bird's beak was one of the many requirements for him to successfully advance to D-Master Rank in the future. Homewrecker Birds were hard to spot and were even harder to kill. The feathers that fell from above the tree were clearly that of a Homewrecker Bird. It was once in a lifetime opportunity for him so he would not let it slide.