Why did Dan kill Henry? And after Roman rendered Dan unconscious, was his sentence increased? And after releasing Marcus back into the wild, again, was his sentence increased? I think they should have showed a meeting with the warden explaining his actions to save the horse as he wasn't trying to escape himself and perhaps they seeing his rehabilitation.
None the less, a beautiful movie.
I'm guessing he tried to kill Henry (I got the impression Henry wasn't dead, just badly injured), because Henry was resistant to continuing to infuse a shirt with the drug that later got used by the bad guys? Just a guess.
Yeah, did seem to me also that Roman should have gotten consequences, after choking his cell mate, and he did in that he was then shown in a solitary, nearly empty cell, but he was also still allowed to be involved with the horse program. Sure seems like he should have been banned from that, for at least a while. That'd be something they'd earn.
I'm thinking he probably pleaded self-defense with the Dan thing. After all, it was Roman who called for the guard. He wasn't trying to hide anything.
Yes, I think we can assume his sentence was increased after releasing Marcus. But that's the point. Sadly, Roman was never going to make it in society. That was what Bruce Dern was alluding to when he said, "Some horses are just bad." Roman knew he meant him, not Marcus. And that's what he had so in common with Marcus. Neither could play nice with others. For Roman, that cost him his freedom. But for Marcus, it meant his freedom. Roman gave Marcus the freedom he knew he could never get for himself.
That's the way I saw it anyway.
I actually saw the ending a little differently. I think the ending offers some hope for our protagonist.
The whole idea about using inmates to train the horses is that it rehabilitates them (the postscript: "Participants are less likely to re-offend"). At the start, Roman is a hothead; see the way he punches the horse in frustration or yells at Martha ("Shut the F- up!"). He also never smiled.
At the end, he's no longer that same person imo. He has a better control of his emotions, his anger. He doesn't kill the inmate who killed his friend, for example; and he had a good conversation with his daughter, recounting his crime to her without screaming or losing his temper. He also smiles / chuckles at the end, at the auction and when he sees the horse out of the window in the final moments.
The daughter, seemingly aware of his change, has a better opinion of him, as she writes that nice letter and vows to let him see her son. The feeling, I think, is that Roman will eventually make parole.