Dermot Mulroney had an “incredibly warm” welcome from the Chicago Fire cast, but the same can’t be said for his character, Chief Dom Pascal. “He starts pretty strong. I don’t think he’s there to be anybody’s best friend,” Mulroney, 60, exclusively told Us Weekly of Pascal’s Firehouse 51 entrance during the season 13 premiere , which airs on Wednesday, September 25.

“He’s gonna lay down the way he sees that things should go.” Us previously confirmed that Mulroney was cast as the new chief after Eamonn Walker announced in May that he will no longer be a series regular starting with season 13 . (During the season 12 finale that month, Walker’s Chief Wallace Boden won the Deputy Commissioner race, which means he will no longer be working out of Firehouse 51.

) Mulroney’s Pascal will have big shoes to fill as the new leader, which the actor told Us won’t be easy to do. “He’s an extremely moral guy. .

.. He’s tested on it a couple of times early in the season,” Mulroney explained, noting that Pascal, who is from Miami, will lay down some “new rules around the firehouse” that don’t sit well with everyone.

He teased, “He’s not there to get along with everybody. By the opposite token, he’s a boots on the ground firefighter.” Mulroney revealed that Pascal “walks right into” all the fire incidents when he first joins the Windy City crew “without any hesitation.

” That shows that “he’s as much a part of taking a fire out as eve.