|“||"Of course. Action Hero Harry. You should meet Sports fan Harry, Master Chef Harry, and Mechanic Harry. the guy does nothing by half measures."||”|
–Liam, "In the Afterlight"
Harry has had military training and previously served in the U.S. military, as well as being a mechanic which lead to him teaching his stepson, Liam Stewart how to fix cars. It is mentioned that his second stepson, Cole Stewart, never fully liked Harry because of his strictness as a parent due to his military past.
Harry Stewart and Grace Stewart met after Grace left her abusive ex-husband, Liam Stewart and Cole Stewart's paternal father. Grace Stewart's car failed on the road, and Harry happened to find her and her two children as he was heading back home from military duty service to open a mechanical garage. He took them to his mother's home and began to work on fixing her car. Grace Stewart managed to find a job and a home near them, and three years later they began dating.