I did a search but couldn't find a topic dealing with my problem, so here goes.

I've just completed "The House Always Wins I" and received the Mark of Caesar/"Render Unto Caesar" from Vulpes Inculta. I was vilified by the Legion prior to receiving the Mark, which has reset my faction status with them to Neutral. I am Idolized by the NCR although I'm not sure if it matters for this quest. I haven't been to the Fort or Bitter Springs although both show on the map. Boone has told me about having to kill his wife but has not suggested we go to Bitter Springs. Now the problem: Boone thinks I'm helping the Legion even though I've not done a single quest for them, and gives me a "CL or me" ultimatum. I had a save prior to receiving the Mark and the setting of my Legion status from Vilified to Neutral seems to be what's triggered this dialogue. As it is, I can no longer talk to Boone. Does this ultimatum take precedence over his sidequest dialogues? Will it be possible to complete Boone's sidequest while having "Render Unto Caesar"/the Mark of Caesar, or is this meant to be done before Vulpes hands over the Mark (or after going to/coming back from the Fort)?

Boone has been with me the entire game and we did his personal quest early on. I have since received the mark and forgiveness from Caesar but haven't gone to his camp. I don't know what needs to happen in your situation but maybe you need to do Boone's quest early too? I think you can visit Caesar's camp without Boone and things will be ok as long as you are not accepted or liked by Caesar. Maybe someone else knows for sure. Good luck.

I'm pretty sure you can do Boone's quest anytime as long as you haven't done anything for the legion.

Just make sure you talk to him at night while hes on duty or else he wont talk to you.

I'm not 100% either because I've always done his quest before getting the Mark. Sometimes only just before, but before. Since he will join with you at the start of the game even if you're "neutral" with the legion, this sounds like some kind of bug/oversight. If you reload that save and get the Mark again, is it the same?

Is he still following you/fighting with you, or is he standing in one place not moving sort of thing? If he's still following you around (hasn't left your employ to go 'home'), you could try killing a few puny Legion respawns to see if that breaks his being stuck into thinking you're helping the Legion. Of course that will give you some bad Legion rep again but maybe just killing a couple would break Boone out and not do much Legion rep damage. Then do his quest and either ditch him so you can check out Legion or take him along to kick some Legion butt. Good luck.

I suspected tooling around the Wasteland and avoiding Camp Forlorn Hope would come back to haunt me. I'll have to try an earlier save. Boone will act normally (following, gunning etc.) and won't force the ultimatum on his own, it only triggers if I choose to speak with him. Or-- the companion wheel works fine.

The bizarre thing is that Boone is seemingly fine with it all until I spent an hour or so decorating the Lucky 38; he's normal when I entered and pissed about halfway through my incremental decorating. Maybe he didn't like my choice of decor. Thanks!

Only other thing I can think of, if it helps at this point, is: If Boone was with you when you received Caesar's forgiveness, reload a save from before that, drop him as a companion, and then get the Mark. I didn't use companions until almost the end of the game, got him well after I had received the Mark but before I had done anything with or to Caesar after that (thus Neutral), and he never said anything odd.