Maybe that Grubb wasn't quite as cowardly as his buddies. I haven't gotten into any staring contests, but I have managed to corner one of them beside one of the buildings after the temple. All he would do is run in place beside me while everyone else hid. After a while, everyone would be inside and he'd just stand there until the other Grubbs came out and started screaming, then he'd start running in place again...
