Wandering NPC's

Just normal zombies, citizens etc. That won’t do anything to you unless injured. They search the attacker and then chase it. Basicly i’d want these because i’m planning to start an RP server with zombies, and if they always attack anything on sight that’s boring. What i’d want to do is people go past them, careful not to touch them, but still them being there, wandering. You know what i mean? Kind of like the scene from Silent Hill movie, when the protagonist sneaks past the nurses.