“No idea how you can be here, but there’s only one person in the universe who hates me as much as you do.”

The chief villain of ‘Amy’s Choice’ is a mysterious character who calls himself the Dream Lord. His identity is teased throughout the episode during which he belittles the Doctor and torments Amy and Rory.

The big revelation is that the Dream Lord is actually the Doctor’s dark half, given form by the psychic pollen. In retrospect we can see how the Dream Lord was mirroring the Doctor both in costume and in his ability to use words as weapons.

Evil twins are nothing new to Doctor Who. Many called the Dream Lord a return of the Valeyard, the possible evil future incarnation of the Doctor. In fiction as a whole there are many examples of dark duplicates of the heroes.

Evil versions of the player characters are very personal opponents in an adventure. The more they can see their own reflection in a villains behaviour and abilities the more their self belief is damaged.

The Doctor Who universe provides plenty of ways a dark twin could come into being. In this case the Dream Lord is a creation of a psychic entity, tapping into parts of the Doctor’s personality that he keeps hidden.

In the end he was actually an illusion but it is a simple matter to create a psionic being that has physical presence. Any alien races that has both the psychic trait and shape shifting could turn themselves into the equivalent of the Dream Lord.

Technology has also been shown to be able to read a subjects mind. These memories could then be implanted in a willing agent or a specially grown clone. These memories could be twisted or the memories new host could be brainwashed into hating the donor.

Several races have created robotic duplicates of the TARDIS crew, including the Daleks. These robots could be designed to ruin a character reputation, wreck havoc from the inside or even go rogue,following their own agenda.

There could be no greater horror for a time traveller than to find out their future incarnation is destined to be evil. There will always be a nagging thought that for all their good acts in the end they will be a villain.

If the chronological nightmare of player characters fighting older versions of themselves is too much for your game there is always an alternative. Star Trek has shown that good stories can be written about the heroes encounter their evil doubles from another dimension.

Although alternative realities are rarer in Doctor Who they do exist and on occasion the TARDIS has accidently slipped into them. It could certainly happen the other way, the player characters evil duplicates accidentally finding themselves in their dimension. With no way home their doubles could cause chaos.

In game terms evil duplicates are easy to create. Simply copy of the player character sheets, adding whatever traits best reflect the nature of their being. You might also want to emphasise negative character traits, for example making a warrior into a sadist.

Once you have created an evil twin, or several sets of twins, you can build an adventure around. They could initiate an adventure by carrying out a twisted version of what the player characters do, messing around with time and helping the wrong people.

Those with a burning hatred of the original might use their likeness to ruin the player character’s reputation or frame them for crimes. They might be jealous of the originals possessions and friends and do everything they can to either destroy them or possess them.

The Dream Lord is particularly effective as we know that some aspect of him exists within the Doctor. For all the good he does there is still the potential for evil within him. Even the Doctor is quick to point out that at 907 years old the psychic pollen had a lot to go on.

Everything he says is something the Doctor secretly thinks or feels, even if his better nature wins out.  We must take all of the Dream Lord’s comments as the truth, used cruelly, but the truth none the less. That is it is true from the Doctor’s perspective.

The Dream Lord taunts the Doctor for his many quirky traits. Just as players might assemble a handful of traits to make them memorable it is no substitute for true character. You can see this in any incarnation of the Doctor, when he becomes particularly irritate his eccentricities drop away and you see his intelligence and fury.

It becomes clear that one of the Doctor’s reoccurring worries is that he will let his friends down. The Dream Lord even goes so far to question whether they truly are his friends or is he just using them to make himself feel young.

Are your player characters actually friends? Would they stay in touch once their travels end? Will they be remembered? Or are they only there to serve a purpose during an adventure.

It can be useful to have a character who questions player characters motivation. In the context of the roleplaying game those selection of people are together because they have been made by the roleplaying group but within the fiction of the setting, why do these people travel together?

Another aspect of the Dream Lord is that he is not really there. Early on it is established that he has no physical presence. He can’t hurt the crew except in an emotional sense. By the same token they can’t simply fight him with their fists, they must use their brains.

This can be achieved by having the villain be essentially an illusion, like the Dream Lord, or have them communicate remotely, for example through television broadcasts. Player characters can’t simply engage in combat to stop them, they must outthink them.

The most enduring thing about evil twins is that even after they are defeated the darkness remains in the characters, sometimes glimpsed in their reflection.