Here is my attempt at a cross between Fate, and song of the lioness, I was considering having Alanna be summoned in place of Saber, but I like her Character too much. I also considered her as archer since she is second only to Diane who is a demigod, but decided against it for the same reason as I like Archer's character

"Bare and silver and iron. Stone for foundation and the Grand Duke of contracts. My great master Shweinorg for the ancestor.
A wall for the descending winds. The four gates shall close and come out the crown. Let the three-forked road to the kingdom cycle."

Matou Sakura Chants. The disgusting worm Zouken is forcing her to participate in the stupid grail war so he can have immortality.

" I announce.
Thy body shall be under my command, my fate shall be determined by thy sword.
Follow the call of the Holy Grail. If thou wouldst obey this mind and this reason, then answer my call."

Sakura doesn't want to fight; she doesn't want her disgusting grandfather to get his wish, but what can she do? The disgusting crest worms in her body prevent her from disobeying. All she wants is to live peacefully with her senpai, and ignore mage craft entirely. Her only wish is to be free of Zouken's control and to be able to live her own life. As she chants she prays to every deity she has ever heard about or read about to give her a servant that can kill her demon of a grandfather so she can be free of him. Shinji can go screw himself for all she cares, but despite everything, all she can do is pity him since he too is trapped by Zouken's will.

"I do swear.
I am the one who shall become the virtue of all afterworld.
I am the one who shall lay out the evil of all afterworld."

As she finishes her chant she makes one last plea to the gods. This time a blanket plea to any god or goddess that can hear her.

"Thou art Seven Heavens clad in the Three Great Words.
Emerge from the ring of control, guardian of balance…!"

Under any other circumstance, her plea to the gods would grant her Medusa who would in time grow to be her greatest friend and confidant. This time however, due to three separate versions of Zelretch from three separate worlds all sneezing simultaneously, a quirk of the kaleidoscope let her plea reach the great mother goddess of Tortall. Hearing Sakura's desperate plea for help from the gods, the Goddess takes a moment to understand Saukra's plight, and another to come up with a solution. She decided. The girl would get a servant. The goddess took one more moment to decide which of her chosen heroes would be able to help the girl. She decided.

There is a great light. A puff of smoke. When the smoke clears, standing in the summoning circle is a woman. She stands a head taller than Sakura, and is wearing gold washed mail and a pristine silver breastplate. On her hands she wears gauntlets of the same color as her breast plate. Covering her legs is more gold washed mail with armor plates of the same silver color as well as armored greaves of that same pristine silver. On her arm is a shield emblazoned with a black tower on a red field, and belted to her waist is a sword with a jeweled hilt with a crystal on its pommel. Her hair is what Sakura notices first. The knight (for what else could she be) has hair so vividly red that Sakura wonders if the knight might be related to senpai. The second and most striking thing Sakura notices is the knight's eyes. Their bright violet hue is almost the same shade as Sakura's hair. The third standout about the knight is the gem she wears around her neck; it is the size of a cat's head; it is black, but flickers like a flame with reds and oranges dancing inside the gem.

The knight looks at Sakura and says, "By will of the Goddess and following the summons of the Holy Grail, I come. I am Servant Rider; I ask of you, are you my master?" Before Sakura can answer, Zouken chuckles, "Excellent girl, you have summoned your servant, now once the last servant has been summoned, you will kill them all, masters included. Once I have my wish, the grail is yours to do what you please." Zouken is lying and he knows it. If all goes well, then Sakura will become his black grail, and he will have access to infinite prana to do what he pleases. If his plans fail, then oh well, he has enough time to wait. Besides, the girl might actually win, if she does, then he can use the crest worms to force her to do his bidding. The thought brings a smile to his face.

Rider looks at Zouken, and when she sees him, she says, "You, you are a demon." This makes Zouken laugh and he responds, "No, we are still standing in my basement are we not?" Rider is confused for a second before she snaps back, "No, you are a soul stealing demon, you are like the Ysander." This time it's Zouken's turn to be confused, but he still chuckles and says, "well then, I guess I should work on my perception of reality." Sakura is nonplussed about this but weakly says, "Rider… please don't." Rider looks over at Sakura and sees the command seals. Her gaze softens and she kneels down and says, "So you're my master huh?" Sakura, surprised at the gentleness in Riders voice smiles a bit, and says, "Y-yeah, by my right of the command seals, I am you're master. What is my servant's name?" Alanna smiles in return and gently says, "I am Alanna of Trebond and Olau, Baroness of Pirate's Swoop."

Zouken looks at the scene, and sees Sakura smiling and he smiles himself. It is not a happy smile like Sakura's, but a cruel smile one that would not be out of place on the demon Rider named him. He could use this, with Rider bringing her up, he could drive her deeper into the depths of despair so she would become the perfect black grail. Zouken chuckles one last time walking away all the while thinking, "A demon huh, that's not a bad idea." There was no way to know it, but at Rider's remark, she set Zouken on a path that Satan himself would approve of.