Dad was back.
After Sam and Dean helped Chuck and Amara reconcile, Amara brought Dad back, right into the middle of the Bunker, as a thank you to both of them.
After the hugs and grins, the "Let me just look at you boys," and "Where the hell are we?" it got awkward: "Tell me everything that's happened."
"Uh, well..."
They sat in the kitchen, Dean made coffee, Sam made grilled cheese, and they told Dad everything, killing Yellow Eyes, Dean's hell, Sam's hell, helping Deacon, losing Bobby, losing Ellen and Jo, the Steins, the Leviathans, the monsters in Chicago, Cain, Crowley, Rowena, Henry and Samuel, Chuck and Amara, the clowns, the Amazons, the Jefferson Starships, they filled him in on anything and everything they could remember.
Finally, when they'd run out of things to say, Dad nodded and looked at his watch.
"It's gettin' late and you boys have been through a lot. Time for bed."
"Bed?" Sam and Dean looked at each other. "You know, we, uh – we don't go to bed this early – uh, ever..."
"Did I ask your opinion?"
"No. No, it's just – " At Dad's stern Dad expression, the answer turned to "No. No, you didn't," and they walked to the bedroom hallway.
"All right," Dad said. "First thing tomorrow, we'll pick up some fresh hunts and get back on the road."
"We'll show you your room – "
"I'll find a room. Go on. Now."
So Sam and Dean went to bed and in the morning woke to find a note in Dad's familiar handwriting. "Went to take care of something. Back later."
They called, he didn't answer. They hacked traffic cams, he didn't show up. They wracked their brains but couldn't figure out what he might need to take care of, immediately, twelve years on from his death.
Finally, at sunset, the front door shrieked open and closed and Dad walked down the stairs. He was battered and ragged and covered in blood.
Dean and Sam stared at him. "What – ?"
"That thing in Chicago? Not a problem anymore." He walked past them, toward the hallway. "Taking a shower. Whose turn is it for dinner?"
Dad was back.
The End.
A/N: The ending of "Bloodlines" always bothered me, that they'd leave all those monsters back in Chicago. (The entire plotline of the episode bothered me even more.)