Kischur Zelretch Schweinorg

He told her that she will sleep until she becomes an adult, and she asked him why he was smiling, because no one at the castle ever smiles. He said that people smile when they enjoy their own lives, which she did not understand due to her unique upbringing. When asked what is enjoyable and when she will understand, he replied that it was a fifty-fifty shot that she would come to that realization, and that due to her long life, she would have many opportunities. Understanding is something gained by chance, like walking alongside the road and tripping over a rock, and once something is understood, it is no longer anything special.

She did not and could not understand, but he said to her that "One day you will notice that life is fun just being awake."

In Fate Worlds:

In Fate worlds, Zelretch did not become a vampire during his battle with Brunestud the Crimson Moon. He found immortality through other means.

When visiting the Mage's Association, he is known to simply take pupils on a whim, but as his tutelage, while comprehensive, frequently traumatizes or cripples the most promising of students, there has yet to be a successor from any of the family lines that follow his teachings. The idea of becoming “a pupil of Zelretch”, the "pupil of a Magician", is synonymous to being turned into a complete wreck, but those that are accepted as the "pupil of a magus" turn out to be fine. When he does appear, the department heads worry over having to send their most promising students in order to force him to leave, but at the same time worry that they will be unwilling or incapable of continuing their careers.

Old mage families teach their children his name, while young families have heard that the great Magician who led the World of Magecraft into battle long ago is still alive.

Nagato Tohsaka is considered to be one of the rare talented pupils that returned without a scratch, but the nature of their relationship was strange. Zelretch met him while both of them were on a journey, and he decided to teach Nagato something as payment for picking up the hotel bill. He couldn't even be called "pupil of a magus" because, from Zelretch's perspective, Nagato was only a follower whom he looked out for every now and then. Their level of relationship was distant, something like that of a supervising teacher who is observing the students doing experiments from afar.

Despite their strange relationship, Zelretch entrusted the design of the Jewel Sword to Nagato and the Tohsaka family. Though there were other candidates to whom he could have given them, such as the brilliant Einzberns and Makiris, they were fundamentally evil. Nagato, while mediocre, was good at heart, so he concluded that "this House will probably never accomplish anything great, but at least they will never stray from the righteous path." He then gave the design to Nagato and told him "alright, it will be a struggle, but work towards this goal". He never expected that only six generations would be needed to produce a result.

He helped oversee the formation of the Fuyuki Holy Grail War system two hundred years ago with Zouken Makiri, Justeaze Lizrich von Einzbern, and Nagato. Nagato allowed his property, Fuyuki City, to be used as the battleground, Zouken proposed the system of "Masters" and "Servants", and Justeaze developed the Heaven's Feel system, offered the homunculi vessels for the Grail, and became the core of the Greater Grail.