Gideon and Rossi will share the screen for the first time on Wednesday's Criminal Minds - well, young versions of them - and fans should expect more friendship than fireworks.
Though young Gideon (Ben Savage) and young Rossi (Robert Dunne) are as different back then as they are now, Joe Mantegna says it's very much a case of "opposites attract."
Check out all this week's Mega Buzz items!
"You'll see the traits that pretty much dictate who we were and who we are," he tells TVGuide.com. "It's not one of those things where we've each changed as we got older. Rossi and Gideon are two different guys, but sometimes that's the chemistry you need to make something happen. He's quiet; I'm more outgoing. It's almost like a marriage in a way - opposites attract, yin and yang. ... You see aspects of his character and my character and how they work in a positive way to help build the unit. I would say they got along very well."
As for the unresolved case that triggers the flashbacks, "The unsub is a guy," Mantegna teases. "It's a case that bothers Rossi to this day."