"No?" Owen asked as he leaned against the wall, folding his arms over his chest. "But demonic possession is?" He tilts his head slightly, a small smile forming at the corners of his mouth.
"I used to be just like you two. Clueless. Then my girlfriend died from an alien in her head. Ahh ahh, yes. I thought it was impossible, too. But I saw it, I was there. I know what happened to my girlfriend." Owen took his glasses off and slipped them into his shirt pocket.
"I am very intelligent, Mr. Holmes. I was only twenty when I became a doctor. Top of my class. After Katie's death, I admitted myself to a mental hospital. Seriously, who sees an alien in their girlfriends brain and doesn't think they're mental?" Owen stared off into the distance for a moment, remembering.
"And then I met him, the guy who'd come into the room and knocked me out. Jack Harkness. I asked him what had really happened to Katie, and he told me. He hired me. He showed me the unbelievable. In Cardiff, there's an agency known as Torchwood. They're above the police, and outside of the Government. They're basically national security, only they deal with the more exotic problems." With a sigh, Owen's eyes focused back on Sherlock.
"Angels exist, too. Guess it makes sense, given that there are demons. Still don't believe in God, though. Not if he's going to let this happen. Aliens are real, space travel, teleportation, time travel. They've even got the ability to erase parts of your memory with a little pill." Owen admits, glancing over at John.
"I've seen a lot in my day. But, I'm retired, now. Only do emergency work for Torchwood. Cardiff was destroyed in the apocalypse. Yes, in this universe the apocalypse has come to pass. So, they've re-established base here, in Lawrence."
Owen knows about John being retconned, and he isn't going to flat out say it. He's sure Sherlock will pick up on the small hint he dropped. And this possibly answers more questions as to who Jack Harkness really is.