Agents of SHIELD's FitzSimmons are the wonder twins of science, but their symbiotic relationship may hit a snag in season 2.

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Fitz (Iain De  Caestecker) and Simmons (Elizabeth Henstridge) took an unexpected swim during "The Beginning of the End," and the near-death experience caused Fitz to reveal his true feelings for his lab partner (see video below). While it is unknown what condition the injured Fitz will be in when SHIELD returns, the series' executive producers promise the FitzSimmons relationship will have a few bumps to work out.

"The beauty of what [Fitz said to Simmons trapped underwater] is it makes for lots of complicated feelings," said executive producer Jeff Bell, according to TV Line. "I'd be curious to see how things will be different or the same now."

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One thing is known for sure, however, Fitz's recovery will be Simmons' biggest interest.

"Let's just say, however she felt in the past now it doesn't matter because the stakes have changed and they're a lot higher for FitzSimmons' relationship," Henstridge told fans at Houston's Comicpalooza. "He is, and always will be, her main priority."

Find out more when Agents of SHIELD returns to ABC on Sept. 23 at 9 p.m. ET.

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