Is Jeanne peculiar?
Undoubtedly, yes.
Her current state is a typical example of a "Pseudo-Servant," or as the Church would say, a "Saint Vessel." The Heroic Spirit does not manifest directly in a human form but instead possesses a being whose soul's wavelength and compatibility are highly matched, using the latter's body to act.
Jeanne's vessel is a seventeen-year-old French high school girl named Leticia, a young woman whose appearance and personality are very similar to Jeanne's.
Leticia is a devout believer and a French national, with a deep-rooted reverence for Jeanne. Therefore, when Jeanne proposed to borrow her body, Leticia handed over control without hesitation, never harboring even the slightest resistance—even though Jeanne repeatedly emphasized that she was not the saint Leticia perceived her to be.
With Leticia's voluntary cooperation, Jeanne bypassed the most uncontrollable step of the Pseudo-Servant process, where two souls merge and influence each other, achieving a state similar to that of Lord El-Melloi II (Zhuge Lang). The difference is that while Kongming's soul resides passively within Waver Velvet, Jeanne's case has Leticia completely relinquishing control.
In this state, Jeanne and Leticia are both interconnected and relatively independent.
Interconnected—Jeanne can access most of Leticia's memories, and the two can communicate and exchange thoughts directly. If necessary, they can switch consciousness.
Independent—Even when Jeanne takes over the body, Leticia does not lose consciousness but experiences Jeanne's actions as if watching a first-person movie. This includes the battles of the Servants and the elementary lessons Shinji gives Jeanne.
When Jeanne accomplishes her goal or dies mid-way, Leticia's body will revert to its original state based on pre-stored information. Depending on the situation, it can even be forcibly transferred to a safe place, and any injuries sustained will instantly regenerate. Hence, no matter how severe Jeanne's injuries are, they won't adversely affect Leticia.
To put it bluntly, it's as if Leticia's existence is enveloped in a shell named Jeanne.
Because they share a physical body, Jeanne cannot dematerialize as a spirit and must eat regularly like a normal person. Though she won't die from starvation, the body will feel significant discomfort from hunger. Engaging in activities as a Servant consumes a lot of energy, and after continuous battles or long periods without food, she can faint from hunger.
Indeed, in the original timeline, Jeanne did make such a mistake. Knowing this, Shinji specifically prepared a bag of food for Jeanne to replenish her energy, hoping to make her realize the necessity of eating while also earning some favor points. Those familiar with Jeanne know that her favorability is hard to increase, but once it does, it becomes unwavering.
Shinji understood Jeanne's peculiarity far better than Jeanne herself.
Normally, a Ruler should manifest directly as a Servant, not as a Pseudo-Servant. Jeanne became a Pseudo-Servant due to historical remnants from the previous Holy Grail War.
During the Third Holy Grail War, one of the Three Founding Families, the Einzberns, who knew the secrets of the Greater Grail, were unwilling to accept defeat and initiated an illegal summoning to call upon an eighth class.
In Shinji's world, the Einzberns illegally summoned Avenger, resulting in the pollution of the Greater Grail, which indirectly led to Shinji's journey through parallel worlds.
In this world, the Einzberns illegally summoned a Ruler—Amakusa Shirou Tokisada.
Amakusa Shirou, a heroic figure from the late Sengoku period in Japan, was known as a prodigy from a young age and grew up to be "handsome and elegant." Originally named Masuda Tokisada, he was later adopted by Amakusa Shiro and renamed Amakusa Shirou. He was a devout Catholic.
In 1630, the Shogunate issued an edict banning Christianity, executing anyone who refused to renounce their "heretical" beliefs within two months.
In 1638, unable to bear it any longer, Amakusa Shirou led 30,000 followers in an uprising. The Shogunate dispatched 120,000 troops to suppress them. Despite this overwhelming force, the Shogunate suffered over 4,000 casualties, while Amakusa's side lost fewer than 100. They achieved several significant victories, causing great panic within the Shogunate.
The Shogunate employed strategies of bribery, threats, and assaults. Eventually, due to a shortage of supplies in the besieged castle and the relentless attacks by the Shogunate's 120,000-strong army, the castle fell. All 30,000 people inside were brutally massacred.
Unfortunately, even so, the Einzberns did not achieve their long-cherished wish. In other words, there was no victor in the Third Holy Grail War.
Due to Amakusa Shirou's activities, the Third Holy Grail War in this world was far more intense than in the other world. This directly led to the weakening of the Three Founding Families. Darnic invaded with Nazi Germany to seize the Greater Grail, which caused significant changes in the timeline.
During the Shimabara Rebellion, Amakusa Shirou witnessed just how despicable, lowly, and cruel humans could become when striving for power. If people of the same race could act this way, how much more would human cruelty accelerate when dealing with people of different skin colors and cultures?
The Third Holy Grail War and the subsequent Second World War further solidified Shirou's thoughts. He concluded that to save humanity, there was no other way but through the miracle of the Greater Grail—the Third Magic.
Afterward, he began searching for various documents and spiritual veins, obtaining information from the Three Founding Families, and seeking the Greater Grail, all while waiting for the Fourth Holy Grail War to begin.
To obtain the Grail, he devised an unimaginably grand plan, with predictions accurate to countless possibilities, even foreseeing the special situation of a seven-versus-seven battle. To ensure success, he painstakingly secured the catalyst to summon Semiramis—not one, but four!
He is the biggest antagonist in this Holy Grail War, the one Shinji is most wary of and must defeat. He is also the main culprit behind why Jeanne d'Arc could not manifest as a Servant and had to descend as a Pseudo-Servant by possessing a body.
"If it weren't for the Ruler's Servant Radar class privilege and the fact that your initial plan was useful to me, I would have killed you already."
Sitting in Gordes' car, Shinji thought this while resting with his eyes closed, completely unaware that an unusual situation was also occurring on Amakusa Shirou's side.
"Never mind, let's stick to the plan. The main goal at this stage is to help the Black faction, counter the Red faction, and incidentally increase Jeanne's favorability. I wonder if that pack of food is enough. By the way, does Jeanne have the 'big eater' trait?" (She actually does.)
Damn you, Takeuchi-sensei, why did you create so many characters with Saber Face? If I get them mixed up, it would be it would be not very comfortable.