How would it react in combat? Or within a city? Maybe when you enter the city it automatically goes to city stables. I get what you mean, something like that dunmer with his guar on loading screen for stonefalls, right? If you ask me, it is not a bad idea.
"Welcome to Arrille's Tradehouse. I barter for goods or coin. I also have a small selection of spells for sale. No credit. You want a little advice? That's free. That's ALL that's free. Would you like to hear about our most popular potions? Our most popular scrolls?"