There are many things you have be aware of in the post apocalyptic world. Raiders, mole rats, and giant mutants are only some of the horrible things awaiting your journey to find your father. If you are tired of being beaten by these horrible freaks, having a follower is your solution.
Fawkes and Charon are both great followers that have potential in saving your butt more than a few times. Fawkes is the best one to get just because he is a super mutant but he is unavailable until later on. So in preparation for Fawkes, there are some things you must do before to get both followers.
First off, you have to retain good karma. Fawkes is a nice mutant and only follows people with good karma. Next, you have to go to the Museum of History and go hire Charon. To do that, go and buy his contract or kill some girl he asks you to kill. After that is over with, play the story line until you get to the part where you meet Fawkes.
I won't ruin the game for you but after all is said and done, you are going to be escaping from the Enclave. When you come out into the Wasteland, you will see Fawkes fighting people. DO NOT TALK TO HIM. Go straight back to the Museum and go re-hire Charon.
After you have re-hired Charon, go to Fawkes and he will join you.
That is how to get two of the best followers in Fallout 3.