During his time in Summer Bay, Duncan befriends Tori Morgan (Penny McNamee), becoming a love rival for Nate Cooper (Kyle Pryor).

[1] McKensy returned for the serial's 4000th episode, based around Duncan's father Alf Stewart's (Ray Meagher) 60th birthday, broadcast in Australia on 8 July 2005.

Duncan left Summer Bay in "disgrace" to live with his aunt Morag Bellingham (Cornelia Frances) in the city.

[3] When his half-sister Shauna Bradley (Kylie Watson) tried to talk to him about his behaviour, Duncan claimed their mother Ailsa (Judy Nunn) never loved her.

[4] Duncan's return marked the first time in 27 years that he, Alf and his half-sister Roo Stewart (Georgie Parker) have been on screen together.

[1] Duncan also befriends Tori Morgan (Penny McNamee) and develops "an immediate connection" with her, but ends up competing with Nate Cooper (Kyle Pryor) for her affections.

After his aunt Celia (Fiona Spence) dresses him in the Stewart family's traditional christening gown, he suffers an allergic reaction to it and is hospitalised.

As Duncan grows older, he befriends Christopher Fletcher (Shaun Wood) and has several surrogate siblings in the form of Blake (Les Hill) and Karen Dean (Belinda Jarrett), Simon Fitzgerald (Richard Norton), Sarah Thompson (Laura Vasquez), Curtis Reed (Shane Ammann) and Aaron Welles (Ritchie Gudgeon), teenagers whom his parents foster.

When homeless teen Mitch McColl (Cameron Welsh) saves Duncan's life, he is grateful and offers him food from the Stewart house.

Nick Smith (Chris Egan) settles in Summer Bay with his family and he and Duncan quickly become friends and get into various scrapes.

The Sutherland family arrive and Duncan and Nick are attracted to the two youngest daughters, Jade (Kate Garven) and Kirsty (Christie Hayes) and begin dating them respectively.

Duncan spirals further out of control when he learns that Jade is dating David Barclay and sets a bomb up in his letterbox which backfires badly.

His presence proves an irritation for his late cousin Alan's son Seb Miller (Mitch Firth) who is now dating Jade.

He antagonises Robbie and Kim Hyde (Chris Hemsworth) and begins harassing Tasha Andrews (Isabel Lucas) when he learns that her biological mother was the late Angie Russell (Laurie Foell).

After pulling a gun on Kim and Robbie, Duncan leaves to join his half-sister, Roo (Justine Clarke; Georgie Parker) in New York City.

After the party, Chloe Richards (Kristy Wright) is killed in a car crash and Duncan is accused by Alf when he resurfaces several days later.

Detective Peter Baker (Nicholas Bishop) tells Duncan the paint taken from his car does not match the one found on Chloe's.

After a talk with Alf, Duncan reveals that Roo's accident helped him put things in perspective and he has changed as person.

A few years, later Duncan gets married and Alf flies overseas for a week to attend the wedding, but they fall out over his wife, Caroline Stewart (Nicole Shostak), and barely speak afterwards.

Duncan catches up with Irene Roberts (Lynne McGranger) and Marilyn Chambers (Emily Symons), but Alf initially refuses to listen or talk to him.