so I know a character named benny is i'm assuming evil because you can kill him at some point (also something about caesars which I think is a faction). Not a lot of info, but Its a bit annoying, not even getting to this yet. Is this a spoiler, and is it main quest?

What you’ve just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response were you even close to anything that could be considered a rational thought. Everyone in this room is now dumber for having listened to it. I award you no points, and may God have mercy on your soul.

Let's sort out few things.
First, refer to the exact game you're talking about, this forum cover all versions.
Second, in Fallout games you can kill anyone. You can kill absolutely important people, but no one is so important that it would kill the game for you, you will just go some other way around, or miss a side quest or two. In F2 for example I once tried to get in the Vault City with false papers, blew it up, and slaughtered the entire city in the result. That was an insane fight but I survived and successfully finished that game, without doing any Vault City quests, of course.

Sounds like you're talking about Fallout: New Vegas, which GoG doesn't sell.

It's part of the main quest.

Ya, RLY. Not only did GOG not sell these when the OP posted this completely (at the time) off-topic nonsense, but they didn't sell it at the time MadOverlord.755 posted, either. Just because GOG just now started selling it does not make the OP any more valid. I suppose to be fair, this was probably an accidental post meant for Steam anyway (and I'm not aware of a way to delete posts).