I'm not sure if "Vampire" is a good term or not. But I was walking around in the subway like I often do, and I came to the place where you escape in the mission 3 Leaf Clover. The service room thing, with the stairs. Well, I walked through, and in the middle room of it, there was a hobo.
So of course I'm thinking 'Odd place for this guy to be'
I pull out my pistol to kill him with, and he makes this weird gurgling growl noise. He jumped on me, and Niko went limp like a ragdoll. The guy's face was like right near mine, and my life began to drain. I couldn't move Niko, and he wouldn't get up, so I just died with the bum on top of me.
Has something like this ever happened to you?
Now look, I know this sounds fucking crazy. I usually hate it when people come on forums and try to start these little bullshit "Myths", but this is honestly freaky. It's probably hard to beleive, but I swear I'm going to get my camera, and record myself when I go down there. I may see it again sometime, and I'll be sure to get a video.
But holy shit, it's just so crazy. Definitely not something I would expect from GTA.