Four characters are up at a castle during a heavy spring thunderstorm. The nearest town is about an hour away on foot. They have a pack horse with them. One character is injured severly (she is unconscious due to a magical spell gone awry) and it's decided to rush her down to the town.
1. Would an average pack horse be trained to allow a rider?
2. How much weight would the average horse be willing to tolerate? One of the characters is humanoid, but unusually dense, so weighs quite a bit more than the average human male.
3. What's the average horse's reaction to going out in what at least will be hevay rain and at most a thunderstorm? I've heard horses tend to be skittish and the rider is not an expert on horses.
I can fudge #1 by having the group of characters arrive by horseback, but that would be a bit unusual (it's fanfiction, and most of the time the characters in question travel on foot, though at least two of them can ride and access to horses is not a problem). I can also get rid of the horses all together and using flight magic all the way, but if the characters have a less-exhausting method for quick travel, they would use it.