Sean Reynolds first arrived in Emmerdale on 10th March 1999 along with his wife Angie, and two children Marc and Ollie. Sean settled down with his family in Emmerdale, and set up his own haulage firm. However, he found himself in stiff competition with rival businessman Chris Tate, who, like Sean, owned a successful haulage firm. Sean's stubbornness not to let Chris gain the upper-hand often got in the way of his own business, and there were several confrontations between Sean and Chris. At one point, Angie suggested that Sean become business partners with Chris, but Sean abruptly brushed this idea off. Sean's establishment as an unattentive husband and unfit father made him notorious in Emmerdale as a potential misery, and he became very unpopular with his fellow residents. In 1999, Sean was a suspect in the disappearance of Chris Tate due to their rivalry, however the real kidnapper was Liam Hammond, who Sean knew. In 2000 Sean attacked Mike Blake for making advances to Ollie. Sean developed a rivalry with Cain Dingle.
In February 2001, Sean's father Len joined him in Emmerdale following the sudden death of Sean's mother and Len's wife Eileen. Sean's biggest storyline came on the run-up to his departure in 2002, was when he embarked on an extramarital sexual affair with local businesswoman Tara Thornfield. Tara had seduced Sean after the pair both discovered that they had developed romantic feelings for each other, and his subsequently been unable to resist temptation. Tara had previously had a passionate affair with another married man, Biff Fowler. Sean and Tara's affair was exposed in 2001, but Sean's wife Angie handled it well. Never-the-less, Sean and Tara decided not to start a life together, as they both felt that it would be a betrayal for Sean's children. However, they seemed to change their minds, and on 4th January 2002, they gave into temptation once again, and drove off into the sunset to start a new life in Chester.
Sean married Tara off-screen the same year and has never returned to the show. However, in 2007, he is mentioned when Angie and Sean's son Marc return to the village for Len's funeral, when Tara explains why Sean was not able to make it to the funeral. He has never been mentioned since but is still presumably married to Tara.