Those horrid images tortured Castiel time and again; Lucifer knew Dean was Castiel's Achilles Heel, so he kept poking at it, anything to act as a reminder that while not all of him had manifested inside the angel, a large part of him had, and he was here to stay. Castiel wasn't sure if they were all just delusions, or how much of Lucifer actually went with Sam when he was rescued from the cage. He knew for a long time that most of his brother was still safely locked away, as he'd told the Winchester brothers once they would have 'felt it' if Lucifer got out, but this whole thing—the walking dead, mass death and destruction—maybe it was Lucifer's doing. Maybe he was out...
When the images finally faded away, Castiel was panting and fresh new blood dripped onto the hardwood and stained his beige trench coat. He'd even gone so far as to try and teleport, but it did nothing but get his wings going and stir up dust in the room. Lucifer laughed.
“You never stop fighting, do you, brother?” He asked, clucking his tongue at him. Then, he perked up, a grin coming to his features and Castiel paled.
“I can feel it, too. I know you know Dean is coming for you. You damsel in distress!” He howled, clapping his hands. “And you. You are going to bring me right to Sam Winchester. We spent a lot of time together, but I still kinda miss the big guy...”
Lucifer rambled on as Castiel looked up to the doorway, smiling softly when he saw a flicker and the room began to get cold with Jo's presence, Dean in tow.