Steve's world is about to be rocked when manipulative Tracy returns to Weatherfield with the news that she is expecting his baby.
Although Tracy (Kate Ford) soon announces that she is planning to have an abortion, viewers will see Steve convince her that she should go ahead with the pregnancy with his support.
Gregson told Soaplife of the storyline: "I think it will split opinions. Some viewers will be willing for him and Tracy to be together, whilst there will be other fans screaming at their television sets telling Steve that he's crazy for getting involved with her again."
Asked whether the pair could embark on a proper relationship, the actor replied: "One thing that Steve realises is that Tracy really does love him and can provide him with the family life that he craves so much. Being together with Tracy would be the best situation for Amy and their unborn child."
To make matters more complicated, Tracy's pregnancy bombshell comes just as Steve is getting on better with estranged wife Becky (Katherine Kelly) again.
Gregson said: "They're getting on really well. She seems to have forgiven him over her losing Max. They really were on course for rekindling their damaged relationship."
Coronation Street airs Tracy's comeback scenes tomorrow at 7.30pm and 9pm on ITV1.
> Coronation Street character 'to be pregnant with twins'
> Coronation Street Tracy pregnancy is the ultimate revenge, says Kate Ford
> Coronation Street Steve has a big choice to make, says Simon Gregson
> Read more Coronation Street spoilers and news
Watch a video preview of tonight's Coronation Street episode below: