Xia Lei and Natalia are facing a veritable dead end.
The island where Xia Lei was located was attacked by both executors and agents. The executors were relatively safe, as their target was only Emiya Norihiko and they would not specifically target the Dead Apostles. The agents were different, as they were the church's combat experts who specifically targeted heretics, and vampires were targets that had to be eliminated.
Each agent could detect and capture the presence of a vampire through its scent. Given Xia Lei's current condition, it was impossible for her to escape the agents' pursuit.
The same goes for Natalia. The closed cockpit and the altitude of the plane meant that it was impossible for Natalia to escape. Even if the missile didn't hit the cockpit, the kinetic energy converted from the altitude would be enough to kill her, no matter how she used magic to strengthen her body, or even being stung by a "dead bee" to turn into a ghoul.
That is why, when the two appeared in front of Kiritsugu, Kiritsugu thought it was a dream or an illusion.
In this regard, Xia Lei and Natalia each gave an explanation.
The fact that she was able to ask Kiritsugu to kill her proved that Xia Lei still had her self-awareness. She knew that she looked terrible and that she couldn't continue to live like this, a life worse than death.
Although she didn't dare to stab herself to death due to her survival instinct, she still tried her best in her own way. After Kiritsugu left, she found a cave far away from the village, locked herself in it, and then used all means to seal the entrance of the cave, waiting to die inside.
Because of her previous blood-sucking behavior, the ghouls on the island have already begun to spread. The agents indiscriminately burned the entire island because the ghouls were spreading and difficult to eradicate, so they had to take such extreme measures.
After purifying the entire island with fire, the agent naturally thought that all the ghouls were dead. How could he have imagined that there were still ghouls who sealed themselves up in order to prevent themselves from losing control of their desire for flesh and blood and coming out to attack humans and animals again.
The closed environment and the raging flames also became the best cover for the smell, and Xia Lei escaped the disaster by accident.
Of course, this does not mean that Xia Lei can continue to exist. The reason why ghouls are called ghouls instead of dead apostles is that they are in urgent need of fresh blood and flesh. This uncontrollable desire will make them become no different from livestock. Without blood and flesh, the ghoul's body will gradually collapse and completely disappear from the world without leaving any trace.
Even if instinct overcame reason again and she broke through the blockade and left the cave, it would be the same because the agents had burned all the living things on the island. There was an inexhaustible supply of flesh and blood in the surrounding ocean, but the fact that vampires could not cross flowing water meant that she could not get replenishment from the sea.
Not long after, Xia Lei, who had lost her source of flesh and blood, became weak and was about to disappear completely. At this time, someone else set foot on this forgotten island.
No, to be precise, they are not humans, but vampires. And they are not half-baked ghouls, but real Dead Apostles.
This person rescued Xia Lei before she disappeared and took her off the island to a shelter for half-baked vampires.
Just as the church would adopt orphans and train them, vampires also had a similar organization. Some dead apostles would travel around the world looking for vampires who were outside the dead apostle circle, and bring them back to give them formal instruction.
To some extent, the Dead Apostles were more attentive than humans when doing these things, because on average only one in a hundred humans could be born as a ghoul, and the probability of becoming a true Dead Apostle was less than one in ten thousand. The low birth rate and the constant attacks by the Holy Church and the Magic Association led many knowledgeable people among the Dead Apostles to seek the development of their tribe, and thus such an organization was formed.
In the shelter, Xia Lei learned that she was no longer a human being but a monster called a ghoul. She also knew that this state was temporary. If she could successfully get through this stage and become a true Dead Apostle, she would be able to control her blood-sucking urges and regain her sanity - at that time, except for the need to change her daily routine and eating habits, she would still be herself.
This gave Xia Lei, who was determined to die, a glimmer of hope. She didn't want to die, and she wanted to see the boy she thought of as her brother again. Before leaving the island, she went to the house deep in the jungle. It was the only place that had not been burned down, and there were no bodies of the two people she was familiar with. She believed that they were still alive - they were magicians with magical powers, and they would definitely be able to escape.
So, Xia Lei settled down in the world of vampires, learning knowledge while trying to control her new body.
Finally, after nearly thirty years, she successfully completed the entire transformation from a ghoul to a Dead Apostle, and was able to leave the world of Dead Apostles and go out into the world. It was Natalia who guided this novice Dead Apostle.
Compared to Xia Lei, who stumbled along the way and was confused, Natalia's experience was much simpler.
There was more than just Bozak on the plane. There was also another big shot who was much higher in status than Bozak. To that big shot, Bozak was just an insignificant ant, so he just watched from the sidelines. Even when Bozak died, he still did not take action. Instead, he restrained his breath and hid himself, allowing the "Dead Apostle Bees" to wreak havoc, turning the entire cabin into hell.
Kiritsugu, who was still very much a navie until then, hit, ahem, the plane with a missile, and had to protect himself from falling into the sea. Although he didn't intend to save anyone, this behavior still gave Natalia a glimmer of hope. Her terrifying desire to survive and her ability to survive once again played a role, and she successfully survived.
But she only had one breath left. What saved Natalie at this time were the "Death Bees" that she had regarded as her biggest enemy and wanted to kill countless times before. Vampires have a much higher survival ability than humans. In order to survive, she took the initiative to be stung by the "Death Bees" to continue her existence.
This action touched the big shot who was watching coldly, and he took Natalia away, who was gradually losing body temperature due to vampirism.
The subsequent development is similar to Xia Lei's. She receives training, learns the knowledge of the world of Dead Apostles, and passes through the two stages of "ghoul" and "zombie" as soon as possible to truly become a Dead Apostle.
Mysteries attract each other, and magicians are much more suitable for transforming into vampires than ordinary people, not to mention that Natalia has the bloodline of a fantasy succubus, and her affinity is higher than that of ordinary magicians. Therefore, although Natalia became a vampire much later than Xia Lei, she became a dead apostle much earlier. In addition, her experience as a bounty hunter also allowed her to quickly become independent, and she did not need to be taught from scratch like Xia Lei.
And because she is also a new savior, Natalia can easily get along with other rookies.
Thus, the two most important women in Emiya Kiritsugu's first half of his life met.
PS: The executioners of the church that have appeared so far, Xiel, Mapo, and Hansa in FSF have never done such extreme things as massacres. The church, which is dedicated to protecting humanity and expelling non-human creeds, will not do something like destroying the entire island directly for killing a ghoul - unless the entire island is beyond saving.
PS2: Yes, it takes such a long time for a normal person to be transformed into a Dead Apostle. Not everyone is a hacker like Yuzuka Satsuki, who can jump from an ordinary person to a monster of the twenty-seventh ancestor level overnight. Not everyone is lucky enough to be directly sucked blood by an ancestor-level Dead Apostle.
PS3: Although vampires are rampant in "Tsuki-hime" and seem very powerful, if you look closely at the list of twenty-seven ancestors, half of them are either dead or sealed. In the final analysis, humans are still stronger.