Sean McPherson is a military veteran.
He is first seen in the final season episode That's My Story. Scarlett voluteers at a shelter for horses who aid the disabled and while cleaning the stables Sean enters a paddock and accidentally releases one of the horses before Scarlett manages to get the horse back into its paddock.
While working in the stables with two disabled girls in the episode Beneath Still Waters, Scarlett asks Sean if he would like to join him but he refuses. She later learns from the owner Dell that he has a lot of personal problems, so when Scarlett looks up the symptoms of PTSD she also finds Sean's Facebook page and watches a video of him performing at his school graduation with a friend.
She later finds him wandering around the streets of Nashville and he tells her that he served in Kandahar so he is used to being in an unsafe environment. She brings him home with her but he turns hostile when she brings up the Facebook video and he mentions the other boy in the clip is his friend Billy, who also served in the military with him but was killed in action.
They show up at the farm together the following morning where Scarlett explains what happened to Dale. They later overhear Sean singing on his own in a room. Scarlett encourages him to get his songs out to the public but after she takes him out for the evening he starts to feel cornered and freaks out. Scarlett drives him back to the farm and is scolded by Dale.
However, Sean soon reveals the horrors of what happened to his platoon and asks to be left alone. Scarlett approaches him again and tells him about an open mic night at a coffee house and he reluctantly agrees to it. He gets up onstage and after his nerves settle he makes it through his song. Afterwards, he shows his appreciation by trying to kiss her and feeling embarrassed runs off.
He plays another gig at the Bluebird but is shocked to see that his wife is in the audience. The wife gets jealous that Scarlett is performing with him but after Scarlett meets her she agrees to have Sean back in the house. Sean visits her and his son but after seeing a Facebook page dedication to a deceased platoon member, he barricades himself in the bathroom with a gun, threatening to kill himself. Scarlett is called to calm him down by talking to him.
Scarlett, Dale and he decide to organize a benefit concert to raise funds for the ranch which has been threatened with closure. He and Scarlett perform together while his wife and son are in attendance. He later attempts to kiss Scarlett but she tells him he needs to be with his wife and son.