Speaking exclusively to Digital Spy, the actor - JJ on the E4 teen drama - said that viewers will see the characters "come full circle".
"It wraps up everyone's storylines very nicely," he said. "When we first met all of these characters had a lot of learning to do, but by the end they've come full circle.
"They're well-rounded people who've learned lessons and you'll see them completed as characters. The audience knows we're not going to be in series five and six so the writers have played to it a bit."
Barbieri added that he is pleased with the material the writers have provided for his alter ego.
"Looking solely at JJ's story, it covers everything that a character like that would do in those situations. I think by the end of the series, every base is touched in the story of JJ.
"I'm happy with how he's turned out - he's almost become a friend that I know now!"
Skins continues on Thursday at 10pm on E4.
> Click here to read our full interview with Ollie