Zouken Matou

Zōken Matō (間桐 臓硯) is the grandfather of Shinji and Sakura Matō. He is also a villain in the Heaven's Feel scenario.

Biography
A shrewd, powerful, but ancient sorcerer, Zōken is patriarch of the Matō family and is known to be the grandfather of Shinji and Sakura. He has amassed a large and extensive library of sorcerous knowledge, yet his lessons are strict and harsh. Zōken considers Shinji to be a disgrace of a sorcerer, and believes Sakura may have more potential than her brother.

Zōken uses methods somehow comparable to vampirism, and actually Shinji's ancestor from two centuries past. He has used a species of magical worms to sustain his long life. Because Matō blood has thinned and no longer produces heirs naturally capable of sorcery, Shinji was incapable of becoming a true sorcerer so Zōken offered to adopt Sakura Tōsaka into the Matō when her father, Tokiomi, decided to train only his older daughter, Rin, to become his successor. Sakura was implanted with Zōken's magical worms to prepare her as a vessel for Angra Mainyu in the fifth Holy Grail War.

In Fate/Zero, it is revealed that after Zōken adopted Sakura, Matō Kariya, a childhood friend of Sakura's mother Zenjō Aoi, became upset that Tokiomi had allowed this to occur. Kariya had previously left the Matō family ten years prior to the 4th Holy Grail War out of disgust for his own family. Disappointed with the lack of sorceric potential in Shinji and Byakuya, Shinji's father, Zōken blames Kariya for allowing the Matō's magical lineage decline since Kariya is the first in many generations to be naturally capable of sorcery. Kariya formulates a deal with Zōken where should Kariya obtain the Holy Grail, Zōken must allow Sakura to return to her family. Due to his lack of formal training, Kariya is implanted with the same magical worms as Sakura.

After witnessing Rider lose to Saber, and enraged at Shinji's incompetence as a Master, Zōken summons True Assassin from the body of Assassin and becomes a Master in the 5th Holy Grail War. Using Sakura as a vessel for Angra Mainyu, the dark spirit that resides within the Holy Grail, he sets out with True Assassin to eliminate the other Masters and Servants.

Sakura soon gives into her dark side and Zōken loses control over her and his plans to acquire the Holy Grail. He is subsequently killed when Kotomine Kirei exorcises his body and Sakura destroys the remaining remnant of his heart.

However, Zōken's presence still remains. As the final battle for the Grail ensues, the last remaining worm of Zōken attempts to reach the Grail, before being interrupted by Illyasviel von Einzbern in her Dress of Heaven. This prompts the long-buried memory in Zōken, and why he has stayed alive for so long. Zōken was a member of the original group who created the Fuyuki Grail, of which the real purpose was to reach the Gate of All Things, the root of the universe. In order to make the Grail, a woman (Lizleihi Justica von Einzbern, Ilya's ancestor) from the Einzbern family sacrificed herself by transforming into the magic circuit of the Grail. At the time, Zōken admired her deeply, and was devastated to see her sacrifice.

He had decided to ensure that her sacrifice would not be in vain by keeping himself alive long enough to witness the moment the Grail becomes completed and reaches the gate. However, as the time went on, the frustration due to the incomplete Grail and the deterioration of his body over such long period had slowly caused him to forget his original intention, and had left him only the abnormal obsession about the immortality. Seeing Ilya in the Dress of Heaven, just like Justica 300 years ago, reminds him of everything, and Zōken finally accepts his end.