'Agents of SHIELD': Here's Why Coulson Is Dying

Agents of SHIELD's 100th episode explained why it is that Phil Coulson is suddenly dying, and it isn't exactly what we expected.

SPOILERS for Agents of SHIELD, "The Real Deal", follow.

In the Season Four finale of Marvel's Agents of SHIELD, Phil Coulson allowed himself to become possessed by the Ghost Rider in order to defeat the rogue LMD called AIDA. There's was an indication that getting to borrow the Ghost Rider's power did not come for free, but Coulson was not ready to tell the other members of SHIELD about the cost.

The deadly consequences of Coulson's decision came to light when Yo-Yo encountered a future version of herself. That future Yo-Yo warned that Coulson was dying and that the SHIELD team needed to allow that to happen. Otherwise, the entire planet would be destroyed.

The first hint of Coulson's affliction, both physically and mentally, came out when he ICEd Daisy Johnson in order to bring her back to the present day against Quake's wishes. He told her that he needed her to lead. When he reached to lift Daisy up, his shirt came a bit open, and a black scar could be seen spreading across his chest.

The sickness became more clear in "The Real Deal". During an argument with Quake, Coulson passed out. Simmons examined him and found that the scar was rapidly spreading necrotic tissue and that the tissue appeared as if it had been dead for years. It was all radiating outwards from the wound Coulson received when Loki stabbed him in the heart with the Scepter just before the Battle of New York in Marvel's The Avengers.

Coulson explained that when he was possessed by the Ghost Rider, the entity's powers burned through whatever mysterious Kree science had been holding his body together since his trip to TAHITI. His body is reverting to the form it would have if he was never revived after being killed by Loki.

The team is upset at the news, especially since Coulson hid it from them. Quake points out that TAHITI technology was available to them when they were still in the future, and that they could have used it on him again if he had only told them. Coulson says he didn't want to undergo that experience again.

Later, Coulson says that while he's accepted his fate, he's in no rush to die. The rest of the season will reveal what lengths SHIELD is willing to go to in order to save Coulson's life, and whether the world will pay the price.

Marvel's Agents of SHIELD airs Fridays at 9 pm ET on ABC.