A/N- This was written for Gallifreybase's Halloween writing challange in 2015. Do enjoy and please feel free to leave me feedback, every little helps. :)
The Doctor, now in his 12th incarnation, poked his head out of the TARDIS door, his eyes darting back and forth as he surveyed the empty street. A heavy mist was starting to fall making it difficult to see anything or anyone.
"Is there anyone there?" He asked, his Scottish accent making even the most innocent of questions sound instantly suspicious and harsh. Silence greeted him and the mist seemed to grow thicker, a gust of wind blowing through the street. The Doctor grunted in annoyance and slammed the door shut. A moment passed before another gust of wind blew through the street and, out of the mist; a short black robed figure appeared. Their face was shrouded by the hood of the robe and in their hand they held a cauldron. A faint murmuring could be heard and a golden glow emanated from the cauldron. With swiftness the figure approached the TARDIS and raised their free hand, revealing it to be young looking but green. Quickly the figure knocked four times on the TARDIS door before stepping backwards and disappearing into the mist. As soon as the figure had vanished the TARDIS door opened and the Doctor's head appeared once more.
"Look, this isn't funny! Where are you?!" The Doctor demanded, his eyebrows coming together as he frowned.
"Four times…..he will knock four times….four times…"
A ghostly voice sounded close to the Doctor's ear, causing him to exit the TARDIS properly and look round. His keen eyes narrowed as he tried to pierce the mist to see the owner of the voice as it continued its mantra. "Four times…..he will knock four times….four times…"
The Doctor whirled round in anger, desperately seeking the owner.
"Who are you!?" He demanded, before coming to a stop and smiling in triumph. There, stood not five feet away, was the hooded figure, their face still shrouded.
"Ah there you are, now then. Who are you and what do you want?" The Doctor demanded as he stepped towards the figure, but, as he did, the figure stepped back and faded away. He frowned and hurried onto the stop the figure had been, searching for them.
"Doctor." A ghostly voice stated from behind him and the Doctor whirled round to find the figure stood in front of him once more. "Ah." The Doctor smiled, reached down and lifted the hood up and off.
"Happy Halloween Doctor." Clara said, a smile on her face. The Doctor pulled a face and motioned towards the TARDIS. "Yes yes, very funny. Come on now, into the TARDIS."
Clara grinned and headed towards the TARDIS.
"And that is the last time I tell you about how my regenerations happened." The Time Lord stated firmly as he followed Clara, who stopped on the door frame and frowned at him. "What do you mean?" She asked curiously, causing the Doctor to laugh. "You know the whole knocking on the door four times and your ghostly voice of knocking four times. All very funny I'm sure for you humans on Halloween but not for me."
"Doctor…that wasn't me. I've only just got here." Clara explained before heading into the TARDIS, the Doctor looked round in sudden concern before entering the TARDIS as well, closing the door behind him. With a groan the TARDIS dematerialised revealing the hooded figure, who simply stayed standing, looking down at where the TARDIS had stood.