The court was told that Stevens - director of Casino Limousines Ltd - began offending against the victim in 1994 when the youngster was just 13. The rapes and voyeuristic sex sessions would continue for 12 years, as Stevens groomed the youngster, plied him with alcohol and gifts, and isolated the fatherless teenager from his mother.
The court was told the victim was first raped when he was 13 or 14.
In an emotional victim impact statement read out to the court on his behalf, the victim said he had trusted "Bob" and looked up to him.
"I was too young to understand the consequences. I felt I had my adolescence stripped away from me."
The victim later lived on the street and suffered post-traumatic stress disorder and frequent nightmares. He eventually tried to commit suicide.
The victim's mother labelled Stevens a pig and "nasty little man". "My mother told me to 'always watch your daughters', but not your sons. Why didn't someone warn me? When I think about Bob I feel sick to the pit of my stomach."