Jack P. Shepherd does Colson Smith's washing for him, which has earned him the nickname "dad".
The "Coronation Street" co-stars live together in a plush Manchester flat, and 30-year-old star - who plays David Platt on the ITV soap - admitted he spends so much time teaching his 20-year-old pal (Craig Tinker) "about life", the pair joke that Jack is Colson's father.
He said: "I live with Colson - and that's a challenge. I have to teach him about life and things, and I do his washing.
"He's like my little project - my nickname is "Dad"."
But Jack admits he enjoys living his life much more so than his alter-ego David, who has endured a traumatic year which has seen him raped and suffering from suicidal thoughts.
He said: "David's had a terrible year full of darkness and drama, but I've had a great year, getting to do this brilliant storyline.
"Our lives are very different, so it's nice to go home and live my life."
Jack's portrayal of David's horrific 2018 was rewarded at the Inside Soap Awards last month when he scooped the Best Actor award - and he is planning to use the prize as a door stop.
He added to Inside Soap magazine: "It's quite weighty, so it might be good for keeping the balcony door open."
Earlier this year, Jack hinted his time on the soap could be up in the near future after admitting he had played out "every single storyline" as David.
He said: "I've been in the show for 18 years now and played every single storyline you could possibly play.
After a while the character must come to terms with what has happened to them and move on, then you can live out other stories. David has been through a lot. He's a resilient character. There are things that he's got over and come out the other side."