I've shot people in cold blood, but always in or near Cherno/Elektro and only when they travel in a well armed group. I'll attack when I feel my safety is threatened. If I can stay hidden and make contact I'll try to make a friendly contact, but if someone see's me before I can say anything, I /always/ assume they're gonna blow me away. The few times I've managed to team up, it was because we'd both talked a bit/shot zombies off each other before we ever saw each other. My point its: If you want to make a friend, find someone, talk with them, THEN show yourself. Seeing a player show up out of nowhere sets off all kinds of red flags.