You should never injure a roo, even if he is mean as it will lead to him not trusting you, and therefore attack you even more. You have to show him you are a strong, but gentle person that will never do him harm, yet will not allow him to attack. Also if a roo attacks, the best thing to do is to stand perfectly still and pretend as if though nothing hurts and that he is inflicting zero damage to you. The roo will be like, "Wow this person is stong!" and he will also know that you do not harm him. He may do this up to three times, but as long as you are persistent he will learn attacking doesn't get him anywhere.