'Agents of SHIELD' 100th Episode Teases Tragedy and Romance for Coulson

Despite making it back from an apocalyptic future AND reaching a milestone 100th episode, Marvel's [...]

Despite making it back from an apocalyptic future AND reaching a milestone 100th episode, Marvel's Agents of SHIELD might be prepping viewers for tragedy.

While speaking with EW about the upcoming century celebration, series showrunner Jed Whedon cautioned fans and said it was an "emotional episode and it was emotional making it."

Uh oh, that doesn't sound promising for the health and wellbeing of our favorite secret agents, especially considering Coulson was infected with Kasius strange substance called odium. Future Yo-Yo warned them that they need to let their fearless leader succumb to the infection and possibly die in order to save the past.

Coulson actor Clark Gregg teased that fans can expect to see a mystery stretching back to the Season 4 finale to be solved in the 100th episode, called "The Real Deal."

"There's been a big scary dagger of fate hanging over Coulson's head all season and we're going to find out the nature of that and what it means going forward," Gregg said, in reference to the deal Coulson made with Ghost Rider. "That in itself would be enough drama for a 100th episode, but on top of that, we have an incredible device the writers have come up with where some characters from the past will appear."

We already heard about the rumor of HIVE and Lash reappearing in the series, but is that all they have planned? Will we get to see Bobbi Morse (Adrianne Palicki) or Lance Hunter (Nick Blood) once more? Or perhaps Antoine Triplett (B.J. Britt)? Maybe Daisy's crazy dad Calvin Johnson AKA Mister Hyde will show up, played by Kyle MacLachlan.

Aside from returning characters, Gregg also teased that a certain fan-favorite romance will have a big moment, though he refused to elaborate which one.

"There is also a moment that many of us have waited a long time for," Gregg said. "I won't say what 'ship it has to do with, but somebody's 'ship is going to reach a shore."

Does that mean the long-awaited courtship of Melinda May and Coulson will finally begin? Or will the adorable coupling of FitzSimmons finally tie the knot, as they alluded to in their reunion earlier this season? Either way, fans should prime themselves for the potential end of the series...

We'll find out when the 100th episode of the series premieres on March 9th.

Agents of SHIELD returns to ABC this Friday, March 2nd, with "All the Comforts of Home."