Author's note: First of all I would not be able to do this without Wikipedia! for all my Mercury needs and facts! To Centauri who pushed me to finish this all by myself and to Saph for extending the deadline! (LOVE YA)
Info: This plot involves the Doctor, Amy, Jack Harkness, and Gwen Cooper. It is set in the timeline after Cold Blood. If this ever gets played any changes are fine by me! Please enjoy.
On a routine pit stop to Cardiff the Doctor opens up his engines and lets the rift refuel his TARDIS. Amy peeks out the door and seeing nothing overly special about the city, she closes the door and leans against it to look at the Doctor. As she turns she turns she feels a surge of dizziness, so bad that she can hardly stand it. She falls onto the stone floor, welcoming the cold. She does a double take and realizes that the TARDIS doesn’t have a stone floor. She hears a male voice that wasn’t the Doctor’s say something and then stop abruptly. Amy looks up and sees a dashingly handsome man that she has never seen before. He smiles at her and says that he is all for gingers but questions how she got in there. Not knowing how Amy had gotten there she notices a door behind her and she tries to flee but its locked. The handsome stranger approaches her, and tells her that she is in the exact spot where his college Gwen just was and asks again who she is and what she has done with Gwen.
Back at the TARDIS the Doctor calls over to Amy asking her if it was nippy outside and if that was why she was closing the door. When there isn’t a response he looks up from his console and sees none other than Gwen Cooper on the ground looking dizzy. Gwen looks up as the Doctor approaches and looks lost. She has found herself in a completely different place than she was just in. Being as defensive as Gwen can be, she stands and asks the strange man in front of her who he is and what he did to her. The Doctor understands automatically that of course Gwen Cooper wouldn’t recognize him since the last time she had seen him he was a completely different person. Trying to explain this to Gwen in his own confusing way, Gwen doesn’t believe a word since his face, voice, mannerisms, even his TARDIS was different than what she had been told it was like on the inside. She tries the door and to her, and the Doctor’s surprise, its locked. Assuming that she is being held prisoner Gwen jumps to all sorts of conclusions, leaving the Doctor with a paranoid Gwen.
Amy explains that she had no idea what had just happened to her or to this Gwen person, but she doesn’t tell the man where she came from, to protect the Doctor until she knows a little more about who she is with. He introduces himself as Captain Jack Harkness, and that she was in the Torchwood facility, but bets that she somehow already knew that. Amy again explains that she knows nothing about what’s going on, and Jack takes it upon himself to escort her to his office to interrogate her further. Amy explains that she was near a door and she turned around and was in Torchwood. Checking the rift meters he sees that there was a small scrape of activity at the time that she arrived but that it didn’t explain how she had gotten in their secure location. Jack asks Amy where the door was and Amy lies saying that she was at a shop in Cardiff.
The Doctor finally gets Gwen to a calm state by recalling the small conversation that they had a few years back. He tries to explain that something has happened to his companion Amy. He asks Gwen what happened to her just before she found herself in the TARDIS and she explains that she was going out for coffee but forgot her wallet and when she turned back she was in the TARDIS. The Doctor checks her eyes and scans her with his screwdriver and finds that she was apart of a temporal shift. The Doctor explains that the temporal shift is usually voluntary. He asks her what it felt like and she describes that she felt overly dizzy so much that it caused her to fall on the floor. The Doctor leans in uncomfortably close and sniffs at Gwen, he begs her pardon and rubs his thumb across her forehead and licks it. When Gwen asks him what he’s doing he comments that she tastes like Mercury and scurries over to the door and scans it with his screwdriver. Gwen worries about the toxic affects that Mercury has and she asks the Doctor if she is alright. The Doctor explains that he doesn’t mean Mercury the element, he means Mercury the planet and that the cause of the shift must have originated from that planet.
Jack, being able to see through Amy’s lies asks her details about her shopping trip and finally asks her that if she was shopping where was her purse or wallet. Knowing that she is caught in her lie Amy explains that she was with her friend, travelling and that she really was near a door when this happened. Believing her now Jack checks his rift meters again and finds that they are all offline. Jack tries to find the source of where this malfunction was coming from but nothing was working. Thinking that Amy must have something to do with this he starts to tell her to fix the problem.
Gwen being lost at what Mercury has to do with anything, the Doctor explains that because both the TARDIS and Torchwood have dealt with the rift, that they are connected only that Torchwood plays with the rift too much and that something as unstable as the rift can sometimes attach or be attracted to someone or something. In their case because Gwen and Amy tried to do the same thing at the same time it shifted them through a Mercury flux tube, the reason he knew that was because primarily flux tube, or Flux tube events as they were properly known, opened windows of the planets magnetic shield. When those events collided with something like the Rift it causes a temporal shift. He goes on to explain that the temporal shift had been there a long time and that it was waiting for an activating event such as the doors opening and closing at the same time. The Doctor expresses his hope that is simply traded places and didn’t drop Amy in the Thames or something worse. The Doctor tries to get contact with Torchwood on his viewer screen but something is blocking the transmission.
Amy finally sick of being blamed for things that are going wrong gives the full details and tells Jack that her friend is a sort of Time Traveler and that he would be able to fix the problem or hopefully explain what happened if she could use his phone, seeing as she left hers on the TARDIS. Jack hearing the description of his old friend asks Amy if his name just happen to be the Doctor. He explains to Amy that he has known the Doctor for a long time and that they are good friends. Amy explains that she has met people before that have said that and turn out to be quite the opposite. Jack understanding this point decides to pull out his mobile and call the TARDIS, but the phone goes fuzzy.
Both parties receive the same message. Just a haunting deep voice, saying that his name is Mercurius a messenger. He claims to be a “God of trade” and explains that he was the one that traded the two devoted women in the men’s lives. He says that everything comes with a price and sometimes that price is death. He tells them that he used the rift to allow himself to come to enter their dominion but that the Flux Tube was broken and only allowed his consciousness to work into the rift. For him to be corporeal he needed to enter through an existing entity, one that had traveled in a flux tube event, namely now the two women that stood before the men. The Challenge was this: The man had to choose which woman would be given as the host for Mercuius by completing the ritual of the Valley of Somnus. Which ever male completed the task first could keep their female. The haunting voice tells them that time is of the essence if neither of them can make a decision then Mercuius will have to start the process by himself.
As soon as the message ends both women feel tired.
Gwen find the lounge seat next to the TARDIS console and sits down. Making sure that she is alright the Doctor checks her pulse and asks her what she is feeling. The Doctor is shocked to find that when Gwen closes her eyes her voice matches Mercurius. The voice plants the seed of doubt asking the Doctor if he thinks he knows Jack Harkness as well as he thinks he does. Gwen opens her eyes and apologizes for falling asleep and ask the Doctor why he is looking at her like that. The Doctor takes a moment and then flies to the console trying anything that he can to see where the signal is coming from and tells Gwen that he will have everything under control as soon as he has a plan.
Amy slumps against the desk and Jack shakes her gently trying to wake her. Jack then hears Mercurius’ voice come from Amy’s mouth and ask him how much he really knows about the Doctor. Amy’s eyes flutter open and sees the half shocked, half relieved face on his face. Knowing that something is wrong and not hearing the conversation that Jack heard Amy demands to know what is going on. Jack tells her what Mercurius told him and then told her that he spoke through her as she was asleep. Amy then makes it her goal to stay awake, and asks Jack where they keep the coffee.
The Doctor starts to talk himself through the clues of where this mysterious ‘Mercurius’ got any power from. Talking to Gwen the whole time putting the fact that she smelled of Mercury, how Mercurius said that he was the God of Trade and how that could mean many different things, but most of all what all translations of the name mercury meant was wages, money, or in a more literal sense, metal. Gwen trying to follow the Doctor in his ramble asks him what metal has to do with why she and Amy were switched. The Doctor brings up his information about Mercury and the flux tubes but most importantly he points out that Mercury the planet is a magnetic compound which is why it is the closes planet to the sun. The Doctor then realizes that this is how he is communicating through Gwen. A magnetic field, but looking down at Gwen’s belly he realizes how dangerous it really is for Mercurius to be speaking through her.
Trying to keep Amy awake they talk back and forth trying to figure out any hidden meanings behind the message. Jack goes through every line of this message and something sticks out to him, The Valley of Somnus. Jack repeats the word over and over knowing that he has heard the word before. He finds a data base on a near by computer and types in the word which leads him to a book called “The Art of Hypnos.” In triumph he turns to show Amy what he has found when he sees her laying on the floor asleep. He rushes to her side and Amy speaks in Mercurius’ voice again. Telling him that he is searching for the wrong thing. Jack talked to the incarnation of Mercurius while holding Amy in his arms, telling him that there was no way that the Doctor would let Gwen die, but Mercurius responds asking Jack how many times he has let him sacrifice his life not knowing if he would wake up again. Mercurius encourages Jack to let the red haired girl be taken, and Amy wakes up again with a yawn. Grasping on what had just happened she asks him what Mercurius said. Jack hesitates to tell her.
The Doctor going through different rooms of the TARDIS gathering different random things in order to defeat this Mercurius at his own game. One in particular is a heavy X-Ray blanket for Gwen. Coming back into the console room he finds Gwen asleep on the chair, chuckling in a deep voice. Mercurius tells the Doctor that his efforts are in vain and that Jack had already begun the ritual on Amy. The Doctor tells Mercurius that he doesn’t believe him because he knew that Jack was not capable of killing his friend, and he continues to work building different random metal contraptions and putting them together. Mercurius asks the Doctor if why he thinks he will spare Amy when he didn’t spare his own flesh. This makes the Doctor pause and look over at Gwen who looks like she is awaking from a dream. She tells him that she doesn’t know why she is falling asleep and he says he has a good clue. The Doctor wraps Gwen up in the X-Ray Blanket and tells her to keep her and the baby safe she needed to keep that on her. Gwen asks what the weird looking contraption that is in the process of being built is and the Doctor smiles, telling her that he isn’t quite sure, but that it was sure to be brilliant.
At Torchwood Jack explains that the Valley of Somnus refers to sleeping humans or hypnosis, and that Amy is not really tired she just thinks that she is. Jack clarifies that Hypnosis is more of a dream like state, or daydreaming, he describes a situation of not hearing someone because you were thinking about someone or something else. That is a form of hypnosis and the trick is to snap out of it while going under. Amy starts to agree when her eyes start to droop again. Jack tries desperately to keep her awake. Mercurius’ voice is heard again from Amy, telling Jack that the Doctor has begun the ritual. Jack choosing not to believe it tells Mercurius that he is wasting his time, that he knew the Doctor would never kill someone like that. Mercurius then puts the question of how many people have died in the line of the Doctor saving his friends before? Jack yells to shut up and startles Amy awake.
Figuring out what he is building the Doctor locks onto the transmission from mercury. He explains to Gwen that Mercurius is using a magnetic field to communicate and that all he needed to do was reverse the polars of the field and the transmission would bounce back to where it came from allowing at least their freedom from the trap that they were in. Using the console and his new device, the Doctor powers up, but is interrupted by Mercurius’ voice coming from Gwen once again warning the Doctor that his efforts are too late. The Doctor now defensive tell Mercurius that he know that he’s not because of the fear in his voice, that the God Mercury was greedy like him, but Mercuirus seemed too greedy, very like a Mercurians of old. The alien race that went to Mercury to absorb the sun but were burnt instead. The Doctor tells Mercurius that more and more it was a fear or a desperation in his voice that perhaps this was his last acts. Mercurius puts an evil smile on Gwen’s face and simply says. I shall take her anyway. The Doctor activates his machine causing the magnetic field to disperse.
Amy is now struggling to keep an eye open and Jack is desperate to keep her alive. He shakes, slaps, and screams at Amy but nothing is working. When Jack hears Mercurius say the words I shall take her anyway. Jack does the last thing he can think of and kiss Amy hard and good. After a few moments Amy opens her eyes and looks at Jack a little bewildered. Jack responds in his flirtatious manor and tells her that he thinks he saved the day.
Having communication restored the Doctor flies the TARDIS near Torchwood and greets Jack as his old friend. They tell each other what they did and try to take credit for the rescue while Amy and Gwen introduce themselves. The Doctor unfolds to everyone his theory of Mercurius being an old settler of Mercury, how they had hypnotic and psychic abilities but that their biggest down fall was their obsession of the sun. Everyone bids each other a sweet fairwell. Jack sweetly kissing Amy on the cheek telling her that she is more than welcome to come back. Amy telling Jack that she will if she ever needs a good snog, and the Doctor telling Gwen to take care of that baby.
Amy returns to the TARDIS and Jack and the Doctor are left to say their goodbye’s. The Doctor tells Jack that its good to see him and goes to leave, but Jack stops him and tells him he’s sorry. Knowing to what Jack is referring to he squeezes Jack’s shoulder in a fatherly type manor and says that he knows before heading back to the TARDIS with Amy.