A product of the Nerazzurri's youth set-up, the midfielder struggled to become a mainstay of the first team, a situation which forced him out on loan to Livorno, whom he would help to secure Italian top-flight promotion in 2012-13.
A two-year-stint with the Dark Reds did little to convince Inter, who again sent the 26-year-old to Sampdoria on loan in 2014. At the end of the season, he joined Il Doria on a permanent deal, signing a four-and-a-half-year contract.
''I never felt hurt [by the lack of opportunity at Inter] because it became a motivation for me because sometimes you don’t get the chance to do what you desire because with football, it’s about choices," Duncan told Joy Sports.
"Every coach and every club have their own choices and they try to build a team in a different way.
''Most of the teams wouldn’t like to play with the younger players they have developed from the youth side. They prefer going out to buy complete players who already have that experience [desired].
"I had this misfortune [of landing] in a team [Inter] where they had all the resources to buy any player they desire so they couldn’t wait for me to develop so they had to give me out on loan.
''I stayed with Inter, six months in the first team, and then I got loaned to Livorno in Serie B - that was my first experience.''
Duncan's stay with Livorno was largely successful as aside from helping the side secure promotion, he made 23 league appearances involving 20 starts in his first season.
In the second term, he played 32 times in the topflight, starting 19 of the matches.
''I went there [Livorno] with anger because after playing in the youth side, I felt I got to a point in my career where I had something to give but I wasn’t given the chance [at Inter] to do so.
"[At Livorno] I was able to demonstrate to everyone that I was ready and that I could do something."
During the summer transfer window, he was linked to AC Milan as well as Inter for a return.