Fabio Zaccheroni is a sorcerer who resides in the Tower of Remnants at the College.
He had black hair with bangs and an undercut and his hair is pulled back in a ponytail with two braids gathered in it.
Personality
Fabio at first glance appears to act like he knows more than the everyone else. The way he acts towards rare things, like a Sleigh Beggy, comes across as perverted.
History
Fabio was part of a group of Sorcerers to the Tower of Remnants (date unknown). The tower houses sorcerers who have made trouble in the world outside of the College and are seeking a shelter either to continue their craft or to escape being killed. Fabio seems to have an affinity for rare objects and is knowledgeable on herbs and minerals that are used in sorcery. Fabio is personally in the tower only to collect flowers.
Plot
While he does seem to be very knowledgeable of sorcery, he also has inside information about secret events such as Chise's auction and the Testament of Carnamagos. He wants Chise for himself when he first meets her, knowing she is a Sleigh Beggy. He tries to convince Chise that he will treat her better than Elias. When Fabio goes in try and take Chise, he grows insect legs out of his back and hands. Chise turns him down and they leave the Tower.
He later appears at the end as extra staff for the College since they are running short. He steps into the classroom and begins a lesson which involves growing vines around the room with the help of a book. Director Bachaman, his supervisor, is overseeing the whole event.
(Source: The Ancient Magus' Bride Wiki)