Agents of SHIELD's inseparable duo of FitzSimmons will start to identify less as a single unit and more as individuals when season 2 opens.

Lab partners and best friends, Fitz (Iain De Caestecker) and Simmons (Elizabeth Henstridge) hit a bump in their relationship when the engineer confessed he had less than platonic feelings for his biochem partner. As Fitz recovers from his near drowning, the pair will have to rebuild their friendship, during which FitzSimmons will becomes less and less on a single identity.

"FitzSimmons always identified as a duo. They finished each other's sentences, they finished each other's thoughts, they completed each others worlds, and now that that dynamic has shifted," Henstridge reveled to Zap2It. "It doesn't necessarily mean it's broken but there's repair work that needs to be done. Then all of the sudden they have to figure out who they are as individuals, which they've never had to do before."

While De Caestecker has said astonishingly little about Fitz all hiatus, Henstridge believes Simmons, for one, will find that their shaky partnership will give her a chance to grow.

"I love the journey that Simmons is going through this season," Henstridge explained. "We're not even a quarter of the way through, and already she is coming into her own a lot more and figuring out her opinions on certain things and the way she's going to operate, because she's never had to do that."

Find out what's next for FitzSimmons, or rather Fitz and Simmons, when Agents of SHIELD returns to ABC on Sept. 23 at 9 p.m. ET. Click the video below to see an overview and preview of the partner's changing relationship.

Tags: Marvel's Agents of S.H.I.E.L.D. television Marvel ABC