I am doing a legion supporter run through and it is pretty sparse compared to a NCR supporter. To make it even worse I rolled a female tribal for the undercover legion operative and was blocked from the Arena as well.
Problems and difficulties I have experienced:
Companions and supporting the Legion
- Boone - will attack and not work with you. Totally understandable with his backstory.
- Veronica - dislikes the legion much much more that the NCR even though the NCR killed her family and threatens the existence of the BoS. She does not care about your NCR rep only that you not wear their faction armor. Completing Legion quests ends up destroying the BoS which will most likely turn her hostile.
- Arcade - hates the legion and will leave you if you help them, has no problem with the NCR even though it was the NCR that killed his father, destroyed his home of Navarro and may eventually track him and his friends down for warcrimes for being Enclave.
- Lily - does not care about anything, only difference is how often she takes her medicine.
- Raul - will roll with you regardless of what side you choose. Has nice things to say about Legion territory and the safety and security it has. Most pro-legion arguments are based upon his statements due to a lack of any other data.
- Cass - will become hostile if you proceed to support Legion victory as the NCR brands you a terrorist.
If you support the NCR all six companions are happy, if you support the Legion 4 of 6 will not work with you leaving you only Raul, who is a great companion, and Lily, who is pretty annoying with her stealth field stand in front of you and your rocket launcher trick.
Legion supporting quests are few and require that you advance the main plot towards the end game final battle. merely completing the first stages of Render Unto Caesar will drop your rep with the NCR even though killing House and befriending the Boomers will be given to you by the NCR as well. The lowering of your rep makes completing Silus's quest impossible.
Completing I Put a Spell on you requires that you say the dumbest thing to the girl threatened by the Omertas. Why would you tell her that the Legion sent you to save her? I chose not to tell a stranger that I was a Legion operative and was blocked from completing the quest for the benefit of the Legion. I had to reload and go back to her to tell her I was Legion so that she could tell me of Capt. Curtiss. Then I could frame the guy and blow up the monorail.
Honest Hearts as a non-legion supporter lets you help the Sorrows how ever you want and lets you kill the Whitelegs. As a pro-legion supporter killing Joshua Graham is set to be relatively impossible with his artificial DT of 50 (it can be done but it obviously is not intended). You can't join the Whitelegs. The best you can do is just kill everyone and everything.
Dead Money does have a cool anti-NCR ending but it also is bad for the Legion. Unfortunately this also ends the game.
In Lonesome Road, Ulysses' comments and actions make sense if you are an NCR supporter. As a Legion supporter yourself it does not fit the storyline very well at all.
Shooting every Legion soldier you find and completing every quest against the legion and for the NCR gets you lots of caps and experience. It makes for a lot of gameplay and the Legion assassins add some spice and a lot of loot. At the end you can still go to the Fort and be nice to Caesar or slaughter the whole camp. Trying that with the NCR turns a lot of the Mojave into a free fire zone, many merchants will not deal with you and many quests will never be issued.
It is hard enough as it is to make a plausible argument for supporting the Legion, missing out on huge blocks of gameplay just rubs salt in the wounds.