Cameron Hunter assaulted the women at addresses in Rosyth and Dunfermline almost three years ago.
The High Court in Edinburgh heard that the 24-year-old took advantage of his first victim when she had been drinking and was unable to give consent.
He removed her clothing, tied her hands with rope and attached a bar to her ankles before raping her.
Months later, he struck again at a house in Dunfermline with a different woman. He compressed her neck, forced her to perform a sex act on him and then binded her with a rope, placed a sex toy in her private parts and raped her.
Attacks were designed to ‘humiliate’ victims
Hunter, of Malcolm’s Way, Stonehaven, was finally brought to justice after the women told police about his activities.
He was convicted after trial, and yesterday judge Lady Scott described his attacks as “extreme and sadistic”.
Speaking about the first attack, Lady Scott said: “You tied her up and raped her when she was intoxicated with alcohol and very vulnerable.
“You must have know she was incapable of providing consent to you.
“These rapes were designed in part to humiliate. These attacks were extreme and sadistic in nature.”
Rapist maintains his innocence – told to get help in prison
The court heard Hunter had been staying in the Dunfermline area at the time of the attacks which happened between July 2017 and October 2018.
Defence advocate Matt Jackson QC told Lady Scott that social workers had assessed his client – who has mental health issues – as being a “moderate to high risk” of re-offending.
Mr Jackson also said his client did not accept his guilt.
He added: “He maintains his position of innocence and that really doesn’t help anybody in terms of remorse or addressing the harms that he has caused.
“He seems to be somebody who has struggled to have normal relationships.”
Jailing him for eight years, Lady Scott told Hunter to seek help while serving his sentence. She placed him on the sex offenders register indefinitely.