Disclaimer: Don't own Star Trek or Doctor Who. Sorry if it starts a bit slow.
The Two Docs
"Doctor, how is our guest?" Captain Janeway strode into sickbay.
"Most unusual, Captain."
"In what way?"
The Doctor picked up his tri-quarter and scanned the man. "Although his appearance is human, he has two hearts, here," he tapped the man's chest, "and here."
"Anything else?"
"Yes."The Doctor sounded incredibly smug. "He also seems to be capable of a regenerative process. He can renew himself if he is dying."
Captain Janeway was beginning to believe nothing could surprise her. Suddenly, Chakotay's voice came through her com-chip. "Captain, please report to bridge."
Janeway smiled apologetically at the Doctor. "Sorry, Doc."
The Doctor began absent-mindedly scanning the man as she left.
The man gasped as he sprang into sitting position. "Where am I?"
"Calm down. You're in sickbay, on the starship Voyager, Delta Quadrant. We found you unconscious on deck 14. I've been treating you."
The man looked confused. "Righty-o"
The Doctor frowned. "What is your name?" He started scanning again.
"I'm the Doctor."
"Ah, so am I." the Doctor replied.
"No. No. Honestly, I am the Doctor. I am called the Doctor."
The hologram looked irritated. "As am I. Emergency Medical Hologram. The Doctor."
"Wow, that could get confusing….. Wait, you're a hologram." The Tenth Doctor leapt to his feet, whipping his sonic screwdriver from the pocket of his blue suit jacket. He scanned the Doctor (EMH). "This is incredible. You're brilliant, Doctor."
"Thank you, but will you stop doing that." He batted the screwdriver away with his hand.
The Doctor smiled chirpily, "Sorry, but I've always wanted to say this. Take me to your Captain."
"Certainly, Doctor."