It was a Rottweiler which was exposed to "something" that made it a little bigger, a little tougher, and a little meaner than the average rotty-rot (I love Rottweilers, btw). You had to do a few things before the dog would befriend you, though. Also, we wanted to make a dog companion that would be a great fighting ally as well.
Apparently this NPC was referred to as the Devil Dog by the Hangdog people. IIRC, I think I heard that you could name him whatever if you got him.
Also, I
think you could tame any old dog around that area (you needed a dog to effectively deal with the Hangdog people) and have him as an NPC. I can't be 100% sure on that tho.
To tell you the truth, I have no idea what you would have to do to get him to join you (normal dogs was a check on some of your traits mainly), but I know that once you have him he does all sorts of interesting stuff for you (especially within the Hangdog tribe, as the better your dog, the better your status).
One of the more interesting NPCs, imo:
The Hanged Man was intended to be the best combat CNPC in the game. Fists, knives, guns - he was master of them all. The player was supposed to be able to find all the CNPCs early on, but they didn't want
The Hanged Man to be *too* good right away. THey were still working on how to limit him
The Hanged Man is wrapped from head to toe in bandages because he's pretty much burned all over. The fact that he's still quite mobile and dangerous is a testament to his badassness. When the PC finds him, he's hanging by the neck from a pole at Fort Abandon, a central Shady Sands-type area in FO3. He's pissed and very much alive, and will tag along with the PC if the PC cuts him down.
Unfortunately,
The Hanged Man is also one of the most evil characters around. Rape, murder, robbery - he's done them all. The tribals know his reputation, and having him in the party will make dealing with them *extremely* difficult. Even the civilized areas are somewhat fearful of him because he's the man with a seemingly infinite amount of lives.
Little is known about
The Hanged Man's history. He'll reveal that he's got a connection to Caesar's Legion, and is particularly ticked off at them.