Forum:Caesar's Legion Ending Problems

I am trying to do all the four different possible endings in Fallout: New Vegas. I am currently trying to do the Caesar's Legion Ending. I have acccidently killed some legions after recieving the Caesar's mark. My fame with them is currently low. Does ths mean I won't be able to complete the game with the Legions. I there any way to regain fame with them again.