So, funny thing
In the original Fallout 3 (aka Van Buren), the first companion you'd be able to find was "the Hanged Man." He'd be hanging from a pole by his neck, but still alive and covered in bandages as if he'd been burned. If you cut him down, he'd refuse to tell you anything about himself other than hint at a connection to Caesar's Legion. He'd also be a super-powerful companion, the strongest combat-oriented companion in the game by far. And you find him right at the start, how lucky!
However, if you've played New Vegas (and especially Honest Hearts), you've probably realized that this guy is secretly Joshua Graham, aka the Burned Man in New Vegas, aka one of the co-founders of the Legion and Caesar's former right hand man, aka one of the most hated and feared people in the entire Southwest. Every tribal NPC or village will fucking hate you, NPCs in towns will be terrified of you, and cause super difficult negotiation situations when he pisses off someone you're talking to.