"Poor bloke. Brilliant mind. He was fine while he was studyin' out of books but then he took a year off ter get some first hand experience..."
-- Rubeus Hagrid (PS5)
In between holding these two posts he took a year off to gain experience dealing with Dark Arts (PS5); unfortunately during this time he met Voldemort in Albania, and by the time he returned to Hogwarts, he was possessed by the Dark Lord. To mask his newfound allegiance he faked a stutter and an eye twitch, hoping nobody would suspect him (PS17), though he certainly made Dumbledore suspicious (DH33).
Quirrell spent the 1991-1992 school year – Harry’s first at Hogwarts – working on an attempt to steal the Philosopher’s Stone, and thus bring Voldemort back to life. His first attempt to steal it, from Gringotts, was thwarted when Hagrid took it from the vault first (PS8) and it was after this that Voldemort decided to possess him (PS17). As Voldemort’s face was sticking out the back of his head, Quirrell had to wear a purple turban the entire school year to hide him (PS7).
Quirrell disguised himself as a "dragon dealer" and bought Hagrid some drinks in Hogsmeade to find out how to get past Fluffy, the three-headed hound in the third-floor corridor. Hagrid let it slip that music would make Fluffy go to sleep, which was all Quirrell needed to know -- and Hagrid got a dragon egg in return. Though he made it through the other barriers, Quirrell-mort was thwarted by the Mirror of Erised. When Harry followed and was able to get the stone, Quirrell tried to attack him – but blistered terribly upon touching Harry’s skin. Dumbledore later explained to Harry that he was protected by his mother’s sacrifice (PS17), and that Quirrell, abandoned by Voldemort's soul, died (GF33).
Traveled widely to learn about the Dark Arts, met a vampire in Romania but also the Dark Lord in Albania.
"Learned in defensive magic theory, less adept in practise." (Pm)
Particular adept at handling trolls (PS16).
Other canon notes and references
According to his biography on Pottermore, Quirrell's hobbies were travel and pressing wild flowers. The author wrote that she viewed Quirrell as a "timid but delicate boy" and the target of bullying for his sensitive nature. Therefore he developed an interest in the Dark Arts as a way to over-compensate and make himself seem stronger. (Pm)
Quirrell may have been meant to sound like 'querulous' which means "someone characterized by complaining; fretfulness." It may have also been meant to sound like "squirrel."
Misconceptions about Quirrell:
A number of misconceptions about the character of Quirrell have surfaced. Most of these are the result of errors in the filmed version of the first book.
- Harry did not see him die in the books, although he does in the film.
- Voldemort did not possess Quirrell until after he met Harry in the Leaky Cauldron in the book, so he shakes Harry's hand and suffers no ill effects. In the film, Quirrell is shown wearing the turban already in the Leaky Cauldron and he pointedly avoids shaking hands with Harry. This is also incorrect.
- Quirrell's year off from teaching was not the year just before Harry's first. The essay Quirrell's Leave of Absence discusses this in detail.
Quirrell in Film
In the film version of "Harry Potter and the Philosopher's/Sorcerer's Stone," the part of Professor Quirrell was played by Ian Hart. The ending of the film was changed somewhat to make it more visually exciting, but in the process some of the basic "rules" of Rowling's world were broken. For example, in the film we see Quirrell fly across the room toward Harry.