haven't seen this mentioned in any tips videos & it took me way too many hours to figure this out. Plenty of people talk about switching between your different characters, but did you know you can party up & go adventuring together?
Hold the up directional button & instead of switching GTA-style, select summon. Once they've shown up, You'll see a Gather prompt on the right-hand side of your screen. Hold the menu button to gather your party.
Obviously, you can't take them on main quests designed only for Kliff, but you can explore the world with Damiane & switch between them very quickly. She gets on her horse when you get on yours. She teleports around a bit, much like your pet, because she doesn't have the same movement capabilities. She doesn't fight as hard as if it was a human co-op partner, but it's helpful to have someone extra when you're taking on some big bandit camps. You can't switch mid-combat, but you can switch without a loading screen while roaming the open world.