Rudy will develop an "odd couple" relationship with new series regular Finn (Nathan McMullen), Strevens told SFX.
"We've upped the humour a little bit more, because as we were writing and as we cast we realised the dynamic between Joe Gilgun and Nathan McMullen... has turned into a sort of a bromance," he explained. "They wind each other up, but they kind of love each other at the same time."
Strevens also revealed that Finn - who has telekinetic powers - is hiding "a dark secret" from the show's other characters.
"[That's] revealed at the end of episode one, and then that plays into episode two," he confirmed. "His secret informs who he is."
Series four of Misfits - written by creator Howard Overman and Jon Brown (Fresh Meat) - will air on Channel 4 in late 2012.
The new Misfits team will face threats including "a six-foot killer rabbit" and the Four Horsemen of the Apocalypse in eight 60-minute episodes.
> Misfits series four cast revealed - New pictures
> Karla Crome: 'My Misfits character is a tough cookie'
Watch Joseph Gilgun discuss series four of Misfits with Digital Spy below: