Shopping with my protagonist

I've been struggling to get a grip on my protagonist's voice in my WIP. Lately I've had to restart every scene in his POV at least twice before it flows at all, and I'm still dissatisfied with the results. I like him, and he's a vivid presence in my mind. One of the voices in my head, if it comes to that. But for someone who can merrily debate with me the events of his era and mine, he's awfully hard to pin down on the page.

So today I decided to try something different. At the very end of the WIP, my protagonist acquires a horse that he'll keep for the remainder of the series. I had a vague picture of this beast in mind, but today my character and I did a little online horse shopping. I'd decided for various reasons that the horse should be a Barb. The character agitated for a Thoroughbred or an Irish hunter, but I shouted him down with story logic. Once I found a good site with images, I recommended this lovely light gray and this magnificent fellow. But my character wasn't buying it. He turned, to paraphrase a local-area mattress store commercial, picky about color. He wanted this bay. And I must say, man and steed will make a magnificent pair.

Now, off to my manuscript to see if my protagonist will be a more cooperative POV character now that I've promised him a horsie at the end if he'll just carry me through the story....