Marco D'Olivera begins as a strict and unwanted NQ Science teacher. Most of the kids think Marco is boring because of his draconian and excessively robotic teaching methods. However, Marco soon changes his teaching methods after he takes Rhiannon Salt and some other pupils on a trip and they refuse to do the work. Marco wows the students with the Coke and Mentos experiment and consequently gains respect from his students.
Marco has a semi-serious rivalry with the other NQT, Guy Braxton. This reaches breaking point when Marco hides Guy's classroom equipment causing him to be put on report. After suffering a panic attack, Marco admits to Guy that he stole the equipment so he would come out as number one. Guy responds by punching him. The two of them appear to be on mutual grounds after this.
In Series 10, Episode 18, Marco also undergoes a brief relationship with English teacher Christine Mulgrew.
In Series 10, Episode 20 Marco is attacked by Rob Hutchinson, due to his romance with deputy head Lorna Hutchinson. Rob locks both Marco and pupil Kenzie Calhoun in the freezer. They are later found by Justin Fitzgerald.