NPC's reaction to different decisions?

I would like to know how to make the person follow and try to kill you, take your weapon, follow and try to kill those who are trying to damage you, throwing you supplies when you need them etc? also how would I make an NPC that shoots and you could even make him shoot just 1 team or shoot everyone who isn't on a certain team? thnx and also how would I make a custom Bubble? like in Stop it Slender, there's a custom bubble... thnx again...