"We hereby propose"

Two teenage girls were sitting cross legged on the floor, their right palms resting on the other's left.

"Place your will in our hands,"

Around them was a large, intricate circle filled with strange symbols.

"And our fate shall rest in your blade."

Ten years had passed since this ritual was last performed, although neither of them was a part of it.

"Abiding by the summons of the Holy Grail,"

They were performing a shared summoning. Both will provide the being summoned with the Prana required for materialisation, but only the elder will be the true 'Master'.

"If you accept and acknowledge this will and reason, answer us."

That was fine. The younger was content with merely seeing him again.

"We hereby swear."

The Hero who saved her all those years ago. She just hoped her memories of him, untarnished by the passage of time, would be enough to call him forth.

"We are all the good in the eternal world."

Because she was certain the corroded piece of metal in front of her would work for multiple legends.

"We are the disposers of evil in the eternal world."

It was supposed to be part of the ship he and his allies sailed on during their adventures.

"You, clad in a Great Trinity of words,

Come forth from the circle of constraint.

Guardian of the Heaven's Feel!"

Sisters Once More

He looked exactly as she had remembered him. Bronze armour over tanned skin; muscular, but not grotesquely so; messy pepper black hair; strong, handsome features; eyes green like the ocean on a calm summer's day.

He looked shorter than in her memories, but that was to be expected- she had been a small child then, and ten years have passed.

"Which one of you is my Master?" He asked, looking between her and her sister, confusion written clearly on his face. She couldn't blame him- both she and her sister were meant to be Masters.

"That would be me." Rin smirked, tossing one dark brown twin tail over her shoulder, as she was prone to do whenever she was making a point about her 'awesome'. Her sister was vain that way. "However, Sakura will also be providing you with Prana." At this, the purple haired girl gave a short bow. "So you may as well treat her as your Master as well."

"I see." Said the Servant, seeming to accept the situation without issue. "Then allow me to introduce myself. I am Servant Rider, and I hope to work well with you in this war." He smiled at them. "I would like to get to know you two before we start fighting, especially why you decided to work together like this."

"We decided to both provide you with Prana because our uncle, who summoned you last war, died from exhausting his Prana reserves." Sakura answered his question, hoping to get the essential information out of the way so that they could get to the less stressful topics. "We figured that you're an incredibly powerful Servant with extremely high cost Noble Phantasms, so we decided it would be more beneficial to provide you with as much Prana as possible to ensure you can fight at full capacity, rather than summon another Servant and limit you both."

Rider seemed surprised to hear that- clearly what they heard about Servants being merely copies of their true selves and not remembering previous summons was true. It saddened Sakura somewhat that this was not the Jack-san who had saved her, but it was still him. "So you're sisters then? It certainly explains why you would be willing to work together in this war. Also, you are quite right about my Noble Phantasms requiring a lot of Prana to maintain, especially if I'm using several at once."

"Oh? You are not questioning our relation, even though we look so different?" Rin asked in what could only be described as a coy tone, forcing Sakura to mentally sigh. It may work wonders on their male classmates, but Rider was a Heroic Spirit, and an adult. He was not going to get so easily flustered by a teenage girl.
He was probably married a couple of times in life anyway.

"I knew a pair of siblings who most would mistake for being of different ethnicities, and my own brothers include a cyclops and a merman with two fish tails. I'm not about to say something just because you have different hair colours, even if purple is very unusual."

Sisters Once More

Servant: Rider

Master: Rin Tohsaka (Sakura Matou is also providing Prana)

Identity: Percy Jackson

Title(s): Son of the Ocean, The Third Achilles, Chosen of the Gods, etc.

Stats:

Strength: B

A demigod of legend who slew the Minotaur bare handed before even learning of the Gods' existence, and having held up the sky at one point -amongst several other notable feats of strength- Percy naturally possesses a great deal of physical strength. Having two Masters supplying him with Prana certainly helps.

Endurance: B

Percy has always preferred close combat, and has received and continued fighting with fairly severe wounds. Baring the Curse of Achilles and after falling to Tartarus, Percy is not easy to fell.

Agility: C

Not the most agile of Servants, Percy is still no slouch, but not quite as agile as one would expect of a Rider.

Mana: B

As a demigod well versed in the usage of his powers, having summoned the ocean itself to Texas and cause a volcano to erupt, Percy has some magic up his sleeve.

Luck: D

Percy's not the luckiest guy out there. Also, he has Rin as his Master, which counts as a Rank down all on its own.

Class Skills:

Magic Resistance: C

He's half god. Of course he possesses a decent level of Magic Resistance.

Riding: A

When your legend involves riding Pegasi and a Hellhound, you get a high Riding skill.

Personal Skills:

Divinity: A+

The son of Poseidon, having been offered to become a god at one point and hosting an Egyptian god in another, Percy has some pretty high Divinity. Will increase further under the effects of Deception of Divinity.

Dream Walker: C

As a Demigod, Percy's sleeping mind tends to wander to relevant events in the past and present.

Eye of the Mind (False): C

Percy's Demigod instincts allow him to react quickly to his foe's movements while still analysing the situation.

Affront to Nature: B

As one of the demigods to combat Gaia, Percy has a greater upkeep than most servants. This upkeep is reduced to normal in the territory of another Servant such as in an enemy's Workshop/Temple/NP or reality marble. Due to his time in Tartarus, Percy is also used to fighting in the enemy's territory, reducing the effect of his opponent's home field advantage.

Noble Phantasms:

Anaklusmos- Sword of Nature's Destruction A

Percy's main weapon, his trusted sword, Riptide. Great for killing monsters and spiritual beings, Riptide can also channel Percy's divine power into the ground, unleashing one of the many natural disasters his father is so fond of.

Perseus- Deception of Divinity EX

When touching water, Prana is replenished and all stats get a rank up. Can control water and is immune to damage from it (heals him, actually). Enables him to converse with equines and aquatics.

Achilles- Armour of Lost Dreams A+

Passively makes him invulnerable to attacks from those with lower divinity, except in his weak spot. Can be activated to give a rank up in all parameters, but acts like a D-rank Mad Enhancement. Costs large amounts of Prana to maintain.

Percy is also capable of summoning his Pegasus Blackjack and his Hellhound Mrs O'Leary. He is clad in celestial bronze armour and has access to his shield.

Sisters Once More

I was honestly not expecting to revisit this story, but rereading Ryuugi's Holding Back the Sea (strongly suggest reading it, it was the inspiration for this whole story) made me wonder what would happen if his story's Perserker fought at full strength without Prana issues, before realising it is a distinct possibility in Sisters Once More, since Rin and Sakura could perform a joint summoning similar to what Kayneth did in the fourth war in order to have both of them provide him with Prana. What you're left with is a ridiculously overpowered Servant who could destroy all of Fuyuki with ease.

I do not plan on continuing this story. I may post the occasional excerpt, but I have no plot for how this turns out- you have no Zouken or CG EMIYA, just Kirei and Gilgamesh.

Gilgamesh is familiar with Percy and his abilities, having fought him in the previous war. Percy will likely have a bone to pick with Caster and Berserker, but I'm honestly not comfortable trying to turn this into a story. Again, you're welcome to pick this story up if you so wish; I even have a line you can use to introduce Archer and their Master into the war:

'Illya hoped they proved more interesting than Archer and his/her Master- Berserker had crashed the both with ease in mere seconds.'

Or you could actually come up with a Master and Archer. Whatever you feel like.

Now I need to get myself to get back to Chapter 1 of Knights of Futures Past and actually post the damn things... Bleh, what is it with me and feeling like I need to jump perspectives constantly? And I really need to get a better grasp of the characters personalities, especially Shirou's.