Immediately come to the stranger's aid, BUT if he is evil he better repent his ways fast!
Choice 1
Give him a healing potion if he pledges his servitude to you, if he says NO, then search his pockets for valuables while he dies.
Choice 2
You stop and think about helping him. If he is evil he could live to hurt others again, if he is good he may go on to do great deeds, or he could merely be an innocent bystander like you. Oops, he died! Ah well.
Choice 3