[s11e1] Out Of The Darkness, Into The Fire Link

As Sam stayed behind to draw the Rabids away, using himself as bait to find a cure for the infection spreading through his own veins, Dean escorted Jenna and the infant to safety.

The black smoke that had roared across the landscape was gone, leaving behind a stillness that felt like a trap. Dean wiped a smear of blood from his forehead, his eyes darting to the tree line. He could still feel the phantom touch of the woman in the black dress, the Mark of Cain gone from his arm but the weight of her words settled deep in his marrow. "Sam," Dean rasped, his voice cracking. "You okay?" [S11E1] Out of the Darkness, Into the Fire

If you want to explore more about this specific era of the show: The psychological bond between Sam’s secret struggle with the Rabid infection Castiel’s torture at the hands of the angels As Sam stayed behind to draw the Rabids

Dean swung a tire iron, the metal clanging against her skull, but she didn't drop. It took three more hits to ground her. He stood over her, chest heaving. "These aren't demons, Sammy. They’re 'Rabids.'" He could still feel the phantom touch of

The first body they found was slumped against a road sign. Then another near a rusted-out truck. These weren't demonic kills or angel smitings. The victims were covered in black, veiny growths, their eyes wide and vacant, as if their very souls had been vacuumed out.

The Darkness wasn't just a force of nature. It wasn't just a cloud of smoke. It was a person. And he was holding her in his arms.