Show them that you are responsible and that you really want some bunniesto join your family. :) Search a lot of information, show your parents often cute pictures, talk about bunnies,…
You could also adopt a ‘fake pet’ (like a stuffed animal) and show that you are prepared to put time and effort in a pet :D
I hope this will help a little bit, good luck!
It’s better for bunnies not to be alone. But if you are really scared because of the fighting incident, you don’t have to take two bunnies. Most rabbits are kept alone, did you know that? Bunnies can live perfectly alone, but they are group animals and will become sad and bored on their own. But if you give him a lot of attention and make sure he doesn’t get bored, your bunny will be happy :)