I'm really going to miss the Sean Roman character. I liked what he had the potential to bring to the show, if only he had been served by better writing.
I liked that he took pride in being on patrol and that he had no ambition to move up to Detective. He was proud of the job he was doing and knew that it could make a difference in people's lives. He didn't view patrol as just an irritating stepping stone to making detective. He certainly didn't put Voight or the unit on a pedestal. He recognized the value that the unit offered in serving the city but he didn't feel it gave them any free passes or diminished his own contributions. He was confident in himself, a good judge of character, a practical realist and not intimidated by Voight, Olinsky or anyone else. He felt the most real of all the characters on the show. I just wish he had been given more to do.
Even his exit was such a lost opportunity. It would have been more compelling to watch it play out over several episodes as Roman had to deal with loosing the very thing that defined him and all the emotional upheaval that would have created. He could have potentially had some nice scenes with Mouse, Platt (especially Platt, as she had been through it herself) and Dr. Charles about that. I also don't really buy that the character would suddenly decide to quit when he could possibly have taken a position as an academy instructor. It was only a few episodes earlier that he expressed an interest in being a field training officer.
I understand it was the actor's choice to leave. I get that and frankly I never really understand why he had agreed to two seasons anyway. To go from strong supporting parts in movies like The Hurt Locker and Flight to playing 3rd fiddle on mildly successful network show for less than 15 minutes of airtime a week seemed like a strange career choice to me. So all the best to the actor. And to the character, Sean Roman...your alternate reality storyline(s) that existed in my head were really good.