Michael shares a turbulent history with Derek and was not pleased when the villain arrived on Albert Square back in November.
Speaking of the animosity, Shepherd told Inside Soap: "It's already been alluded to that Derek and Michael didn't get along in the past. The true extent of Derek's emotional and physical bullying of Michael still hasn't been revealed, but Michael's well aware of how unpleasant he is. Derek's a nasty piece of work."
Asked whether Michael could try to settle the score in the future, the actor replied: "Absolutely! Michael holds grudges and doesn't forget anything.
"He has a bad feeling that the Brannings will become too powerful in Walford if Derek continues to ride roughshod over everyone, so he's definitely in Michael's sights. We can expect these two to clash, that's for sure."
EastEnders fans will see Derek target the Moons next week as Tyler (Tony Discipline) and Anthony (Matt Lapinskas) owe him money and cannot pay it back.
With his brothers in trouble, Michael faces a dilemma over whether to help them despite his recent problems with the pair.
EastEnders continues tonight at 7.30pm on BBC One.
> EastEnders' Anthony, Tyler will need Michael's help - Spoilers
> Read more EastEnders spoilers and news
Watch Michael's EastEnders character trail below: