The Swordswoman Saga is a Highlander/X-Files crossover. It starts off more in the Highlander style with more X-File properties coming later.
The Highlander universe features people called immortals who can potentially live forever. Provided they keep their head attached to their bodies. They are involved in a battle called "The Game" although the whole thing is deadly serious. They are destined to fight until there is only one left. Not all immortals go looking for a fight but there are always those who do so any immortal has to be ready with the sword.
New immortals, if they are lucky are found by another immortal and taught the rules of the game and how to use a sword. If they aren't, they either end up the lackey of the older immortal or worse, easy prey for any immortal who wants an easy quickening.
The quickening like a lightning show. After an immortal is beheaded the winning immortal gains the power and the knowledge of the immortal he or she had defeated and the power is released in a not too subtle, explosive manner which could be mistaken as lightning.
Immortals appear as normal as any mortal they would run into. However, unlike their mortal counterparts they do not age. So while they may appear to be say, twenty-something years old they may actually be hundreds even thousands years old. They also heal very quickly from ordinary cuts and fatal injuries are merely "kill" them temporarily. Eventually they come back. As a result they must be careful to conceal what they are so as to not make their existence public. Imagine what the CIA or Cancerman would do if they got their hands on an immortal.
Immortals can tell if another immortal is in the area by their presence, or buzz. It's kinda like feedback when they are in proximity to another. It helps to keep unscrupulous immortals from sneaking up behind them. (It can still be done but not as easily)
The movie, "Highlander" features Connor MacLeod the series his kinsman Duncan. Duncan has considerably more baggage including a thieving girlfriend, Amanda, a cynical friend and the oldest immortal alive, Methos and a watcher Joe and his own student Richie Ryan.
Why a crossover? Well this came about because I always said headless bodies and weird electrical activity sound just like an X-File. I know I'm not the first one to say it. Hell I'm not the first one to write a crossover either. But this is the way I spend my time.
The Swordswoman stories feature a twenty-something immortal named Reina Molestador. She has two brothers, one deceased, one an FBI agent. Her mentor is a friend of Duncan MacLeod.
The story begins during season 5 of the Highlander Universe and season 4 of the X-Files universe.
Story 1: The Loss PG-13. There is some language that you might not want the kiddies using.
Story 2: Mercy Tendered. This one takes place a few weeks after The Loss and sometime before the Highlander episode "Money No Object."
Story 3: The Shadow This one takes place sometimes after "Mercy Tendered" and after the Highlander episode "Money No Object."
Story 4 is actually two stories in one. The events which take place are exactly the same. The point of view is what varies. They're called Musings and Musings II.
Story 5: Holiday Disaster (R) This one takes place after Musings. In the X-Files Universe it takes place sometime during Season 4 before the cancer arc and before the Episode "Comes a Horseman" in the Highlander Universe.