Hello again every one hope you are going to enjoy this chapter in some way it is setting the scene for later on in the story we are back with the twin again but Sirius and the Doctor will make an appearance again.

As always neither Harry Potter or Dr Who belong to me they are the property of J K Rowling and the BBC.

Chapter Nineteen

The twins made their way quickly behind a wall hanging that seemed to be covering some brickwork, Angela grabbed Harry's hand and pulled him along with her, seemingly passing through the wall or so it appeared to him in fact the bricks were just an illusion somewhat like the entrance to platform nine and three quarters. Harry closed his eyes and let his sister pull him along with her, feeling the magic wash over his skin. Opening his eyes once they were on the other side, his twins eyes seemed to be glowing a little and he knew she was seeing things that he could not. Ancient torches set in rusting brackets sprang to life at their presence. As the twins moved forward along the passage more of the torches flamed into life while the ones behind them seemed to be snuffed out once they were no longer needed.

Putting one foot in front of the other and drawing Harry with her Angela set off down the ancient passageway, it looked long disused and she did not look down to see what she might be crunching under her feet, instead she followed the shifting colours of magic that she could see, there were several coloured ribbons of light but the one she felt was the one she wanted was a deep purple, it seemed to be the strongest and gave her the feeling it was the oldest.

The passageway seemed to slope downwards as the silent pair advanced on their torch lit way, at one point the passageway branched and Harry waited quietly until Angela chose the way, it was not the one he would have picked as the slope seemed to tilt upwards for a few hundred yards till it once again began to slope downwards. The twins gripped each other's hands as a cool wind began to blow gently caressing their bodies with each step they took it seemed to pick up speed and intensity, till it was making their hair and clothes stream behind them and they were battling their way against it each step becoming more of an effort as they fought against it.

"Just a little more." Angela muttered as Harry began to wonder if they would get any further.

Then with one final set of forced steps the wind stopped as gently as it had begun and they stood panting and smoothing their hair down, taking a moment to look at each other before grinning at each other.

"Wow that was intense." Harry said a little breathlessly.

"Yeah." Angela grinned at him. "Ready to go on then?"

Harry grinned at her. "Oh yeah lets go, this is almost as good as the running."

"Nothing's as good as the running." Angela replied before taking his hand again and pulling him onward. "Gotta love the running."

"Did you notice?" Harry questioned. "That though the wind was blowing us around, it had no effect on the torches?"

Angela nodded, her eyes focused on the purple ribbon of light. "Yeah, that's magic for you guess it must only work on living things you notice we aren't crunching things under our feet anymore?"

Harry nodded and did not bother replying, though he could not help wishing he could see what Angela could. They continued downward for maybe ten minutes more before they came to another branch in the passageway, while Angela studied what only she could see, Harry pulled out his wand and made a mark on the wall just in case something happened so they had more trouble finding their way out.

After a few seconds Angela pulled him to the right, again the passageway sloped upwards this time quite steeply; however Harry was happy to trust his sister and follow her lead. They turned a corner and for a second he found himself questioning her choice as the passage seemed to dead end in a stone wall, Angela however did not hesitate but walked into the stone work. Harry closed his eyes and felt magic wash over him though this time he felt a little resistance as he passed through it. Once on the other side he glanced back and saw through the illusion to the brick passage beyond it before Angela pulled him on.

On this side of the illusion the passageway looked older instead of brickwork it was hewn from the living stone that the castle was obviously built on; there were still torches that sprang to life as the approached them. However instead of being in brackets these seemed to be actually pressed into the stone, they looked older too, soon the twins noticed that it was growing colder and moisture was coating the wall and instead of the crunch of something under their shoes there was the splash of the occasional puddle under foot.

They still headed onward and downward, following the glow of magic only Angela could see, till they reached what appeared to be a maelstrom of light and energy. The twins halted looking at it though Angela's eyes travelled over the walls looking for something though Harry was not sure what. The young witch let her fingers run over the wall before giving a tight little smile and turning to look at Harry.

"This needs a sacrifice." She said softly as their eyes met.

"A sacrifice?" Harry parroted not liking the sound of that.

Angela smiled then before running her hand over the stone which cut it open allowing her to smear some of her blood on the wall. "Yeah a little of our blood, just guessing here but I think that's how the magic recognises that we have a right to be here."

Harry shrugged and followed her example cutting his hand on the rough wall and smearing his blood next to hers, as soon as he had done so the energy barrier parted allowing them to continue on.

"Hey look it's all healed up." Harry stated showing his sister the healed cut on his hand.

Angela looked down at her own once again unmarked palm and smiled. "That's magic for you I guess."

Harry grinned at her as they hurried on their way, they did not have much further to go the passageway narrowed a couple of hundred yards further on forcing them to turn side on to get their bodies through this portion of the passageway, an adult would undoubtedly have to squeeze through the narrowed part. Almost at once when they got through the narrow section the passage opened out into an underground cavern. As they entered the dark space soft light began to glow from the walls getting brighter as they stepped in till it was brightly illuminated.

The pair of them looked around, the walls were decorated with a few paintings, there were four people depicted in one good natured smiles on their faces.

"Slytherin, Gryffindor, Ravenclaw, and Hufflepuff." Harry said looking at them all. "The four founders of Hogwarts."

Angela wandered around looking at the paintings there was Hogwarts itself looking new and fresh, its windows blazing with lights. There were magical creatures and wizards standing side by side, looking over at the school, and then there was the depiction of a familiar blue box and a somehow familiar man standing beside it.

"Dad." She whispered, though not as quietly as she had thought for Harry rushed over to join her.

The pair continued to look around the chamber the paintings on the wall were varied and fascinating, there were pictures of Arthur and Merlin (the seventh incarnation of the Doctor). As well as other notable events from history, though at first the pictures seemed to be static the twins noticed that they were in fact moving just very slowly, as when they got back to the pictures of the founders they had changed into what the twins could only assume were their animagus forms of a Lion, a Badger, an Eagle and a snake.

Having examined the pictures and smiling at some of them before taking the time to see that Godric and Salazar were slowly rough housing and messing around while Helga and Rowena looked on with indulgent expressions, the twins finally turned their attentions to the rest of the chamber.

The floor was obsidian that looked to have been polished, though it was not slippery to their feet as they moved over it, the black glass appeared to be lit from within giving the floor a strange other worldly glow. In the centre was a raised pillar of obsidian about three feet in height on which sat a large stone with runes carved into it. This was it the ward stone for the castle, as the twins walked closer to it they saw that there fainter runes traveling down the pillar and out onto the floor though they seemed to be weak at best. The two children passed over them easily and stood by the pillar looking down at the ward stone.

"Now what do we do?" Harry asked as his fingers itched to reach out and touch the stone.

Angela reached out grabbing his hand and pulling it back before he could connect with it. "We need to key ourselves into the wards using the stone." She said softly taking his hand she pulled him away and back to the pictures. "Here look at this one." She continued pointing the scene depicted on the wall which showed the four founders and the doctor gathered around the ward stone though they had to notice that the doctor was now shifting before his seventh incarnation and the one they knew as their Father, a boyish grin on his face as he did so. "See what they are doing?" Angela asked.

"They're putting their blood on the stone." Harry said in awe as they watched for a couple of minutes. "Their lips are moving too, they're saying something but I can't tell what."

"Blood, DNA, they're leaving a DNA signature on the stone, a marker for their descendants to repeat so they can be added to the ward recognition." Angela surmised.

"So we have to add our blood too?" Harry questioned.

"Yeah but it looks like there is a ritual involved as well." Angela ran her fingers over the painting and slowly the Doctor; their Dad turned his head to look at them and winked.

"But we don't know the ritual." Harry sighed as Angela's fingers dropped from the painting as she turned to look at the pillar again.

"So we make up our own." Now she was looking at the fainter runes that emanated from the pillar but were not on the stone. "The stone has the original wards look but the others have been added over time, some of them are messing with the original intents of the founders and look at that one that's some sort of curse." Harry nodded seeing what she meant. "The auxiliary wards have been added remotely though I don't think anyone had physically been down here in a long time."

"So we have to create our own ritual to add ourselves to stone." Harry added. "Then we can have some control over the wards?"

Angela nodded with a smile on her face. "Yeah and then we can move around more freely, now we just have to give it a little thought."

They looked at each other their minds racing as they tried to think how this could go. Each one trying to think of words to say for the incantation, it needed to be something that identified them as the Doctors children, Merlin's kin.

"From Merlin's line." Angela whispered looking at Harry.

"From Merlin's bone." Harry added a second part. "Merlin's blood flows within."

"We are his line, our blood his own. " Angela went on.

"We add our blood upon the stone." Harry put in the next bit.

"And claim this castle as our home." Angela added softly, they looked at each other. "Well it sounds good shall we do it?"

Harry nodded his head as this time he allowed his fingers to caress the stone, giving a slight start as he found a sharp silver knife black with age resting within in, his fingers closed around the hilt and he pulled it out. He wiped the bade off on his robe seeing the tarnish fall away and the knife gleaming in the light. Looking at his sister he pulled the blade across his palm seeing the blood running between his fingers before handing her the blade Angela did the same then clasping hands they held them above the stone letting their blood drip down before intoning the incantation they had made up.

From Merlin's line

From Merlin's bone

Merlin's blood flows within.

We are his line, our blood his own

We add our blood upon the stone

And claim this castle as our home

As their blood dripped onto the stone the eyes of the pictures turned to watch them, to see what was going to happen. At first their mixed blood just lay on top of the stone, then slowly the runes began to glow and slowly their blood ran over the surface of the stone before sinking into the runes. A sound like a massive bell sounded in the chamber deep and soft at first, the wave of sound running around the chamber gathering strength, as it bounced off the walls till it rumbled like thunder before dissipating through the walls and echoing softly through the castle the noise fading the further it went, hardly noticed in the inhabited parts of the castle and certainly not in the headmasters study where Dumbledore had discarded the parchment and stood gazing out of the window, pondering the riddle that was Harry Smith.

However the sound was heard somewhere else, in London if fact, the sound echoed in the Tardis itself and out into 12 Grimmauld Place echoing around the library drawing the attention of both Sirius and the Doctor.

"What's that?" The wizard questioned his head turning to the blue box.

"That, not sure, could be important ,sounds important, big noise like that, must be something good right, shall we see I think we should see don't you?" The Timelord replied dropping the book he had been looking at and heading for his ship.

Sirius sighed and followed the other man; he had to admit the Doctor made life interesting he's seen things he never would have believed possible other worlds, aliens, and he had his freedom and his godson back. The Doctor was already well inside the Tardis when Sirius got inside and with a shrug of his shoulders he transformed into Padfoot and followed the Timelord's scent deep into the Tardis. He found the Doctor in a room quite deep inside the ship eventually and entered before transforming again.

"Doctor?" He questioned looking at the bell that hung from the ceiling wondering if that was what he had heard.

"Fancy a trip to Hogwarts?" The other man asked. "It looks like someone has got into the ward stone chamber and added themselves to it, the ward stone that is not the chamber." He gave the wizard a little smile. "Do you want to bet that it's Harry and Angela?"

Sirius gave a grin that was one bet that he was not going to take; he was coming to know his godson and his sister well enough to know that it was probably them.

"Let's go I know you can get past the wards." He replied.

The Doctor spun on his heel without a word and Sirius followed him as they headed back to the control room with a few deft movements the Tardis was dematerialising and heading for Hogwarts.

Angela and Harry looked round as the sounds of a very familiar engine sounded and the Tardis materialised in the chamber and two very familiar figures bounded out. Sirius drew Harry into a hug while Angela and the Doctor smiled at each other before he hugged her.

"It's been a long time since I was here." The Doctor remarked once all the hugs were done and he looked around, pacing over to some of the painting and looking them over. "In fact it looks like no one has been here for a long time, however someone has been meddling." Now he was examining the secondary runes, before looking over at his children and Sirius. "I think we need to run a few repairs here, first though we need to add you to the wards Sirius."

The wizard gulped before heading over to the ward stone followed by the children, the Doctor directed them where to stand and asked for their right hands cutting each one and then his own he directed them to hold their hands over the stone.

"I the Doctor, known to the wizarding world as the wizard Merlin, do hereby add the house of Black to the ward stone in the person of Sirius Black and his heir who is my son Harry Smith." The Doctor intoned.

The blood of the four dripped onto the stone and was absorbed by it and the bell sounded once more.

"Okay." Sirius said softly as he pulled his hand back noting that the cut was healed. "Why did you want to add me?"

The Doctor smiled at the other man. "Because the wards have been messed with, and while it only takes one person to mess with the wards right now, it takes four to put them right." He smiled holding his hands over the ward stone not touching it but pretty close. "If you will do the same with your hands and let you magic flow over the stone I will see about sorting some things out."

The other three did as he asked before Harry questioned. "Why does it need four of us?"

The Doctor smiled. "We each one of us represent one of the founders, four of them four of us, they set the original wards I just watched as a sort of overseer."

Slowly the auxiliary wards began to glow and shift as the Doctor concentrated on them a few vanished all together some changed and some were absorbed into the stone. Finally as the other three began to feel quite drained the Doctor pulled his hands away and gestured for them to do the same.

"There it's done." He said at last giving a brief sigh. "They've had some right cowboys working on them over the years, I told Godric it was not a good idea to let the head teacher alone have control over the wards from the head's office, I suggested having at least two people needing to agree." He ran a hand through his hair and led the way to the Tardis. "Also it looks as if someone in the headmaster's office managed to curse one of the teaching positions in the last couple of decades."

The four entered the Tardis as the Doctor walked over to the console and began to fly his ship. The trip was a short one and they ended up in one of the corridors near the great hall. Opening the door he looked out before exiting and waving the others to join him.

"Now since you two managed to add yourselves to the wards that means you can go pretty much anywhere, there are some secret rooms that pretty much no one knows about including the private rooms of the founders and of course mine." He smiled at Sirius's shocked look; the marauders had never found anything like that. "Please use them responsibly and try to stay out of trouble." The twins grinned at each other at those words knowing just how unlikely that was. "I've also reset the alarms, if anything threatens the castle or if there is something here that shouldn't be that bell will ring, the more strikes the worse the danger, it will take them a little while to register since in the past things and creatures have been let in here that could be perceived as a danger to the children learning here or too the castle itself."

"I guess we should really be getting to dinner." Angela said suddenly. "We spent most of the afternoon finding and exploring the chamber."

The deep tone of a bell sounded just as she said that causing the four to look at each other.

"That would be our cue to take care of something that should not be here." The Doctor began before the bell sounded again. "Make that more than one thing that should not be here, Sirius I believe we should go and sort this out."

"Dad did you forget Sirius is still a wanted man?" Harry questioned.

The Doctor had the good grace to look a bit sheepish. "Oh yes I'd forgotten about that."

Sirius grinned. "I have an idea, Harry get out your wand and say Accio James Potter's invisibility cloak."

Harry did as Sirius said and after a few minutes delay a piece of material flew into Harry's hands, it was silvery in colour and he could not hide his shock.

"That is James's invisibility cloak." Sirius said looking at it. "The fun we had with that while we were here if your Dad had, had that when Voldermort came calling you could all have hidden under that and he would never have found you." He sighed softly. "Dumbledore was fascinated by it though and asked to borrow it so he could examine it, still the cloak is yours."

Harry shook the cloak out and draped it round his shoulders laughing as his body vanished from sight, before pulling the hood over his head and vanishing completely.

"Nice, like a perception filter only better." The Doctor commented. "I take it you are hoping to borrow it Sirius." He continued as Harry took the cloak off again.

"If you don't mind Harry." Sirius looked at his Godson who reluctantly handed the cloak over. "I'll make sure you get it back once we are done." He told the boy putting the cloak on and vanishing from their sight. "Shall we go Doctor?"

"Oh we shall." The Timelord replied. "You two go on to the meal, you need to eat and build your strength back up, see you later." He told the twins before he lead the invisible wizard up to the third floor.

Angela and Harry looked at each other before heading off the great hall, though both of them would have liked to go along on the adventure they were very hungry. Joining their housemates at the Slytherin table they filled their plates and began to eat hungrily.

"Where have you two been?" Draco asked looking at them.

"Exploring." Harry replied between bites of food.

"Plus the potion I made did not agree with me too well." Angela added reaching for a goblet of water and giving the pumpkin juice a glance of dislike.

Albus Dumbledore sat at the head table looking out over the hall watching the students eating his eyes coming to rest on the Slytherin twins who had apparently been conspicuously absent from classes during the afternoon, while he could have punished them he preferred to leave it to their head of house still hoping to win the boys confidence and hopefully get him to admit he was in fact Harry Potter. The twins seemed to be aware of his eyes on them and glance over at him before looking away and turning back to their food.

Once the meal was over the pair with their group of friends headed to their dorms to settle down and get on with their homework. Angela's vision had long since returned to normal, though she was feeling unusually tired and for once spent all night in bed. While Harry on waking the following morning found his invisibility cloak folded at the end of his bed. He quickly hid it in his trunk before any of his dorm mates woke for the day.

Well there you have chapter nineteen I hope you enjoyed it and would appreciate any reviews. Please also read the authors notes below as they are an explanation of how and why I identified the Doctor as Merlin

In the Battlefield episodes in the 26th season of the original run of Dr Who shown in 1989 the doctor who was then played by Sylvester McCoy is identified as Merlin by first the knight Ancelyn then Mordred and finally by Morgana.

I have no idea if the founders were animagus but I decided to make them so and have their forms be the animal associated with their houses.

Obsidian is the naturally formed volcanic glass.

I wanted Harry to have James's invisibility cloak but with Dumbledore unsure as to Harry's identity he probably would not just give it to him this way Harry gets to have it and Dumbledore has another puzzle to work out .

Sorry if the incantation is not very good it was the best I could come up with and sorry for the wait for this chapter I've had and still got a nasty little eye infection which is taking its own sweet time to clear up.