I found this quite interesting.
EVERYTHING BELOW IS A SPOILER
Summary
So I wandered the world some after I woke up in Rattay, and managed to acquire enough loot to buy and pimp out a decent horse… Then I got on the Main Quest track. Pretty soon I was hunting rabbits with Sir Hans. And here’s where the game surprised me.
My 1st playthrough, I didn’t have a horse and and all the cut-scenes reflected that. I figured that was always what the cut-scenes would show. And so Sir Hans gallops off chasing a wounded boar and you have to track him down on foot. You find Sir Hars’ dead horse and dogs, and Sir Hans himself tied to a tree, prisoner of 2 Cumans. You thus have the option of sneaking in and freeing him without fighting, doing stealthy murder on the 2 Cumans, or fighting them straight up, whatever suits your fancy.
But if you have a horse, things are way different. First off, the cut-scenes show you keeping pace with Sir Hans on your horse during the chase of the boar. Then the cut-scenes show the chase running into the Cuman camp. Sir Hans’ horse is felled by an arrow and Sir Hans does a face-plant on a rock, KO-ing him. At which point the cut-scenes end with you fighting the 2 Cumans. After you kill them (which isn’t that hard), you go check on Sir Hans who wakes up just then and is quite impressed that you took out the Cumans. He gives you much less shit later as a result.
Thus endeth “The Prey”
Then, without so much as a by-your-leave, off you go to war as a response to the raid on the Neuhof stables. They’ll give you Pebbles but your own horse will certainly be better in all respects so ignore Pebbles. From here on, Pebbles is NOT “your” horse. It will not come when you whistle and will always respawn back at the Rattay upper bailey whenever you turn your back. Also, you inventory remains with your previous store-bought mount.