First off, I'll start off with how whiny-sounding the lone wanderer's voice is from Fallout 3. Personally I didn't care about the prologue, living as a child with the restriction of not fighting back at Butch(He somewhat pissed me off the first time I played FO3), but later as I play through the prologue every time, I feel dedicated to eating the sweetroll just to troll Butch. Butch is kind of an asshole, but he can be a helpful companion sometimes.

Secondly, both the Talon company AND regulators just love to piss me off, depends on what side I'm playing, so when that happens, I'm forced to go to their headquarters and make martyrs of their leaders as a warning that they will be next in the killing fields should they provoke my wrath any further. It seems simply just a one time, one thing for me thankfully. Regulators may be annoying when playing an evil character for instance, but the Talon Company is at the top of my most hated list, shoot to kill, search and destroy. I mostly have a tendency not to blow up Megaton because of my paradon example in the good characters I play, so it's very likely the Talon Company is a favorite target of mine, and I don't attack them alone. I bring an army(Enclave Commander modded STAG troops or SKMC marines to kill me so mercenaries and paint the grass with their blood, always a pretty sight to torture inhuman savage evil in broad daylight). But I don't try to be a hero, or an absolute villain in general gameplay. I try to keep things balanced in a manner of perspective I see fit.

Rivet City, oh don't even get me started. Almost everyone down there, I sincerely fucking hate. Human garbage at best for kind of survivors, they got a poor attitude when greeting newcomers, that aggression is expected because probably they've been survivors of raider attacks and talon mercenary attacks, I don't know the reason and I don't care. Rivet City is one of my most hated places in Fallout 3.

List of NPC's I hate in Fallout 3:

** Vault 101 people - For casting you out of society for no fucking reason if you did nothing wrong, and your old man should be the one for them to blame, not you.
** Colin Moriarty - I don't 100% hate him, but he's kind of an asshole.
** Harkness - Self explanatory. The asshole mall-cop down-syndrome of some security chief he is. Yeah, tough guy. Act all tough, c'mon. We love to see those reflexes, and you talking trash, makes you feel good, does it? I hate this guy absolutely, with a passion. Before entering that shit can Rivet City, I always pull out my sniper or a silenced weapon and assassinate this dickhead whenever I want to enter Rivet City without being harassed by him.
** Those slavers at the Lincoln Memorial - Because nobody tells me what to do. I go where I want, do what I want, and no man alive or dead commands me. They are met with the retaliation of my bullets and shrapnel.
** Princess from Little Lamplight - Does her majesty require me to express my royal hatred for her highness, or does she simply attract my ire to wound her in a verbal assault expressing how she has no friends and Mayor McCready hates her?

I'm personally just annoyed how everybody calls you the 'courier' ingame. Playing Fallout New Vegas is not my personal task to be a mailman, full OR part-time. I consider myself mostly as a soldier, no. A commando, assassin, squad leader, I don't know. Why not just be called the wasteland warrior or something? Because I got the skills and traits of a warrior ingame. I love how the game is based on choices like Deus Ex for instance. There are of course things I love, and things I hate in the game. I am only going to mention the people and factions I hate.

** New California Republic - Nothing 'new' about it. NCR alright. I offered alliance to them when I first started the game, I should've known. Only a small deed means a small factor to them, how much more must I go in NCR politics to gain their mutual respect? That is when I knew. They are the very founding reason why I hate Republicans. They make a good example of their greed and corruption in real life. But again, that's just with politics in real life. Back to FONV...

I will say for my most hated part is security detail trying to prevent their president from getting killed. I should be a fucking guard, not a goddamned civilian with no power watching Kimball's speech. When you ask someone to be in vow of service to security, you should let them do their job, or don't ask them to do security sweeps at all, period.

I also notice how poorly they treat the residents near Camp Golf and within Freeside. Near Golf, kids are wanting, needing food and water to survive, and how NCR was trying to make them starve to death like it was the communist era. Freeside on the other hand, yes I understand NCR's convoy was attacked by lowlife murderers on the streets, but then again, it just makes NCR as bad as them. So they only give food and water to 'NCR' citizens, and how the King himself took offense to that because neither him or the non-radical residents of Freeside weren't able to receive any food.

That is when I learned the truth about NCR's darker side of the background. They were attacked by the Great Khans no doubt, so they retaliated at Bitter Springs and took more lives than what justice demanded. They killed children, the poor and sickly, but most of this was done by members of the 1st Recon unit, or so I was told. Boone, Craig Boone himself, who many endorsed as an ally and companion for those who have good relations with the NCR themselves, I can't say I ever took Boone on any scenarios with me, but all I know for common is I have no sympathy for the man. Evidence he is drenched in sin clearly states from a 'love' letter saying how he 'enjoyed' killing the weak of the Khans like cattle. It was clearly evident to me that Boone is a war criminal, so he's made an enemy for life. Well, he's made extremely powerful enemies with my empire, all my soldiers will certainly be out to assassinate his sadist ass. All I can say is, Boone certainly will have no safe haven from me and my allied coalition and imperial forces...

In general gameplay, the encounters of NCR bounty hunters and legionary assassins are what annoys me the most. The legion doesn't fuck around, wastes no time and downright gets to killing, that's not a problem for me. What my main gright of this problem is the bounty hunters, who think they can 'police' you, greet your player talk all tough like and say 'you got 3 days to live unless you fix your reputation with NCR blah blah blah', SHUT THE FUCK UP!!! I DON'T CARE!!! I OFFEND YOU ON PURPOSE, SO SHUT UP, AND GET TO THE KILLING, NCR THUGS!!! That's what triggers my hate factor, that is what fuels me to do more damage to NCR than I have already done. NCR in general, is essentially corrupt. I don't accept a 'lesser' evil. I may have more than three reasons in which I despise NCR's presence in Nevada, but I know for a fact I will never side with NCR again. I don't hate NCR because they talk tough. I hate NCR because they're fucking annoying. Tough people won't waste their time talking, but clearly I can see NCR is weak.

** Crimson Caravan - NCR's favorite bootlickers. They've certainly earned the reputation of being terrorists to my nation Because I hate the NCR at heart, these little terrorists take up arms and dare have the nerve to attack me when I'm alone, or if I have soldiers with me. So I retaliate, leaving their little trading post in fire and ruin. I have honor at least to not engage civilians, but anyone else who sympathizes with NCR ingame YET they take up arms and try to fight back, my military will treat them like that of enemy combatants, and they will most certainly, be shot in my line of view...

** Caesar's Legion - Considering I may have more respect for viking culture than the Romans, why not? Because 51 BC Rome is a perfect example of imperialism. Caesar's Legion, no different than the enemy I love to burn in the past, I could even summon an army of dragon riders and have their mounts burn down Imperial camps in Skyrim, but we're talking about Fallout New Vegas. There are other factions that may have some potential connection to Rome, some of these factions are not in the game for instance. Why do I hate the legion? Simple. Brutal slavery, prejudice against women, and just plain, flat-out evil. Women serve them no better than slaves, or personal pleasure to Caesar's officers. Their language and the understanding of the old era codecs looks pretty badass for something not too modern, but their doctrines and beliefs on how to run an empire is something  I won't allow. NCR may be scared of the Legion to resort to fall-back and ambush tactics, but if the Legion should fear anyone the most, it will be me. When they sleep and close their eyes at night, subdued to their sub-conscious, tortured by their thoughts of guilt for all the evil they have done, it will be thoughts of me and my soldiers that they are tortured with. I will be cruel to the legion at best. Sure, they may be good with melee, but they are no match for STAG's CQB, and our ancient dragon knighthood. I will use whatever is necessary to take down the enemy, be it charge up and personal, or set up traps and flashpoints if for instance it may be defense missions. I'm gonna say for the least legion centurions are hardly any challenge to me, but NCR using stolen Brotherhood of Steel armor for their power armor, bitch please. They're no match for my battle mechs.

** Boomers - Some-what I hate them in a way. There are things I like and things I hate about them. Sure they're trying to defend themselves from the dangers and cruelty from the outside world, but they do exhibit a hostile kind of behavior, it just depends on my threshold of how much verbal garbage I can tolerate from most of them. What really provokes me in killing them is making derogatory comments about my canine companion(If traveling with one). They're alright if you play your cards right, but be prepared to get your hands dirty if you feel the Boomers turn evil, and feel the need to pull the plug.