Tommy tracks down Kirsty and convinces her to return to Weatherfield next week, oblivious to the violence she has forced Tyrone Dobbs (Alan Halsall) to endure in recent months.
As Tyrone and Kirsty (Natalie Gumede) reunite, Tommy's girlfriend Tina McIntyre (Michelle Keegan) is horrified over his meddling and lets him know what Kirsty has been up to.
An appalled Tommy later takes matters into his own hands when he spots that Tyrone has a suspicious burn.
Fountain told All About Soap: "Tommy instantly jumps to conclusions and assumes Kirsty has burnt him, but actually she hasn't. Later on, Kirsty's having one of her temper tantrums, mouthing off that Tyrone fancies Tina, and Tommy just can't hold back any longer. He tells Kirsty that he knows all about what she's been doing to Tyrone."
He continued: "[Kirsty is] humiliated and furious that Tommy knows about her violent behaviour. Tina's angry with Tommy for spilling the beans, and Tyrone's furious with Tina for betraying his confidence. Tommy and Tyrone have a big falling-out."
Fountain added that Tommy may have taken the wrong approach in his attempts to help his best friend.
He explained: "Tommy just wanted to protect Tyrone, but I think he's overstepped the mark blurting everything out in front of Kirsty. I would have sat Tyrone down and tried to get him to open up about what's been going on. But things don't always go the way they're planned."
Coronation Street airs these scenes on Monday, August 27 on ITV1.