FATE/Probability

After the discussion kiritsugu said 

"I am going to give you a summary about magic crests, so don't interrupt me in the middle and ask anything that you hear for the 1st time. Ok?"

Looking at his son nodding his head he continued.

"As you know the Magus family lines are established based on bloodlines, they pass down 3 things used to maintain their superiority and compound their chances to reach root with the passing of generations."

"They are sorcery traits, supreme mystic codes and magic crest. The other 2 are not relevant now hence we will talk about the magic crest."

"Independent Magic crests are created by taking either a mystic code or a piece of a phantasmal species and implanting them in your body. This process has fatal dangers as well as the consequences are not small in the case of success."

"Once a magic crest is created, the magus who has it would slowly convert some of his magic circuits into a part of the crest and store all the information about magecraft he has and his research into it like a library."

"For example, your friend the current head of the tohsaka family, has her family magic crest that easily allows her to use magecraft if she has an affinity for that magecraft. So magic crest help in casting spells as well as support the magecraft being performed."

"The next important ability of magic crest is that they accumulate mysteries as they are passed from generation to generation and accumulate recorded information. They are essentially a grimoire attached to you. Hence they are a source of stable mysteries passed down through generations."

"This effect allows for maintenance of a semblance of stability in this age of declining mysteries."

Shirou having heard this and seeing his father pause, hence he took this chance to ask. 

"What are the consequences of having a magic crest, and how is it supposed to help our situation?" 

Looking at the boy`s genuine question kiritsugu opened the notebook that he used to teach shirou and started writing as he explained. 

"In the end even with all their advantages the magic crest is foreign to the human body, transferring the crest is like accepting an organ transplantation. The chances of failure are high and rejection even more."

"In case of rejection, most subjects die horrible deaths, hence mages pass on the crest only to their direct descendants, as their bloodline has developed some tolerance to having a crest attached to itself."

"Even direct descendants just have a higher chance of success and no guarantee. Again taking your friend as an example she suffered from continuous burning pain and is dependent on medicine till her body adapts to her crest even when she is the direct daughter of her father."

"So mages normally implant the crest onto the next person piece by piece and over a long period of time.

Then after Sirou`s repeated inquiries, kiritsugu explained to him how normally there is only one crest and hence it is passed on to the next head candidate. This is also the reason for the existence of the legitimate heir to a magus lineage.

He then talked about how having a crest means being the family head of a magus lineage and the representative of them in the eyes of the magus association. He then talked about the blood bath as well as the competition that happens for it in bigger families. Kiritsugu said 

"Magic crests have another function. that is they preserve the life of their owners as long as there is prana in them."

After saying this he continued and stated

"Now my reason for saying all this is I want to ask you, shirou do you wish to take the emiya family magic crest?"

Looking at his confounded son kiritsugu explained. 

"You don't have to answer now, before answering you have to learn about the history of the family and as well as myself."

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(kiritsugu explained his family`s past, his past, the sealing designation and damage to the emiya crest.)

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"So shirou this is why I only have 40 per cent of my crest. I wished to let the emiya family end with me."

"But you need the crest more than me as it will act as a protective umbrella for you by giving you the identity of a family head and it will preserve your life in case of your origin`s spontaneous stimulation by your visions."

Looking into Shirou's eyes with a serious gaze and taking a pregnant pause the 4th head of the emiya family asked. 

"So shirou are you willing to take the emiya crest despite the danger of rejection due to you not being blood-related and also suffering continuous pain as the crest adapts to your body." 

Hearing this shirou began pondering deeply as the scene of the berserker and caster mutilating his body revolved in his brain and he didn't feel the fear he felt the 1st time it happened to him instead he was filled with a strange fighting spirit and thought.

< I DON'T WANT TO DIE! But I have to feel pain if I have the crest.>

< If feeling pain is my fate then I will have it on my own terms instead of someone else`s.>

With his eyes filled with fighting spirit and determination lacing his boyish voice, he said 

"I am willing, no dad please pass on the crest to me."

Hearing this kiritsugu`s face was calm on the outside but his heart was in turmoil and he screamed internally. 

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…

A week passed without any incident and shirou went along with his days in routine. Kiritsugu had removed the combat practice in the morning and added physical training along with the supplements.

Under Kiritsugu`s guidance shirou practised swordsmanship as well as exercised while flooding his body with flowing prana, thereby increasing his performance. Shirou had started feeling burning pain from his circuits very similar to when he opened them.

Kisitsugu said that shirou was overloading them and should let them grow but shirou pushed his body till the heat was bearable and stopped to avoid damage in his circuits.

Time passed and the term exams were on the heads of children and shirou focused extra on studying to get better marks in the exams.

By the time the exams were over, summer had already begun and it was already April. During these times kiritsugu tried to teach shirou other basic make crafts but learnt the hard way about the significance of origin and element.

The same origin and element amplifies the specialisation making learning other magecraft harder than necessary. Having witnessed the mediocre results of Shirou's attempts kiritsugu was forced to advise shirou to practise the basics that every magus should know.

He taught him shields, body enhancement, direction or consciousness spreading and then gave him the book about the basics of runes as well as the forging of mystic codes. Kiritsugu explained the basics of sympathetic magecraft, some familiar creations as well the mana transfer but skipped the parts for which shirou is too young to know. 

Time passed and shirou practised a lot of things and he and Rin started meeting more because she was easily able to guide shirou on the things he wasn't able to do.

Shirou`s swordsmanship mastery also increased but he still was getting thrashed by taiga.

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The school declared a holiday for a week before declaring the results of the term exam. Shirou was cleaning the residence when the doorbell rang.

Rushing to the door he discovered Mr. Raiga as well as Mr Fujimura and Taiga standing outside. Welcoming them inside Raiga said 

"Little shirou I learnt from taiga that you are improving in swordsmanship by leaps and bounds."

Embarrassed shirou lowered his head as Taiga pulled him into a hug and said to her grandfather while holding shirou

"Of course, he would improve who do you think is teaching him."

Kiritsugu came out of the room under the boisterous laughter of the old man. Then the two friends greeted each other.