Does this mean Holly never got sick from Jonathan getting hit by the arrow?
Well, in part 3 everyone developed Stands relatively recently (compared to the start of the arc) because Dio only pulled himself out of a coffin, I thought? But obviously that never happened to Dio in this universe, and also it says on the first page that Jotaro was a Stand user from birth. So if it affected Holly at all maybe they resolved it long ago, or maybe--actually, http://danbooru.me/posts/2053272?pool_id=10133 says Holly has a Stand, too. In canon she had vines growing out of her back so maybe it's like Joseph's. In any case, she must have a hardier constitution here, even if she seemed pretty normal in the few frames she appeared in!
I'm calling it right now, the villain in this story, the same person who stole the Stone Mask that started this in the first place, is Straizo.
I thought that was pretty obvious.
Lord Jonathan claims that this arrow gave him a Stand.Only OneSo it takes more than that to be a Stand User then.This is a special arrow crafted from meteorite. Countless others whom yearned for a Stand were stabbed by this arrow.Nearly all of them were said to have suffered a high fever for 50 days and died in agony. They died!?Even the unrivaled Ripple user Straizo was not enough.In addition, Master DIO became a Stand User when he resonated with our lord.He can see other people's Stands, yet he himself lacks the capabilities for a Stand. So far, the only Stand User born directly from that arrow is Lord Jonathan.