According to the Daily Star, Michael will become fixated on Ronnie (Samantha Womack) in scenes which air this summer, sneaking into her bedroom to watch her sleep and rooting through her underwear drawer.
The newspaper claims that the mysterious businessman will also ask girlfriend Roxy (Rita Simons) to start wearing the same perfume as her troubled sister, as well as spreading lies about Ronnie in conversations with Kat and Alfie Moon, whose baby she snatched on New Year's Eve.
A Walford source commented: "Everyone knows Michael has a mean streak but he is set to get a whole lot worse. He's trying to meddle in as many people's lives as possible. It seems he wants Ronnie all to himself. But what exactly is he up to?"
Michael has been an enigmatic figure since his first appearance on the Square last year, but fans have already seen him scare Ronnie with his nasty side.
EastEnders' executive producer Bryan Kirkwood has also compared Michael to the late Archie Mitchell, one of Albert Square's most memorable villains.
Michael's new storyline is reportedly being filmed at the moment and will air before Ronnie's departure from the soap later this year.
Read more about EastEnders' Michael and the future of the Moons:-
> 'Enders star discusses Michael future
> EastEnders reveals new Moon arrivals
> 'Enders star excited over Roxy, Michael future
> EastEnders exec excited about David Essex role