Avery attended Hogwarts School of Witchcraft and Wizardry in the 1970s and was sorted into the Slytherin house. He, and his friend Mulciber, amused themselves by playing nasty pranks on other students, including Mary Macdonald, on whom Mulciber tried to use Dark Magic during the 1975-1976 school year. Avery was also a friend of Severus Snape, something that bothered Lily Evans, who was Snape's best friend at the time. She found Avery's sense of humor to be very sadistic and could not understand how Snape could associate with him. According to Sirius Black, Avery was part of a "gang of Slytherins" who later became Death Eaters and also included Bellatrix Black, her future husband Rodolphus Lestrange, Evan Rosier, Snape, and Wilkes.
First Wizarding WarEdit
Sometime during the First Wizarding War, Avery was apprehended by Ministry of Magic officials and stood trial for being a Death Eater. Avery was one of few who "wormed his way out of trouble", according to Sirius Black, since he pleaded the Imperius Curse. He was not sent to Azkaban. He was also one of the Death Eaters who didn't search for his master after his downfall.
It can be assumed that Avery assisted in the Quidditch World Cup riot a year before Lord Voldemort returned, though this is not proven.
Second Wizarding WarEdit
Avery was the first Death Eater to crack and grovel at Lord Voldemort's feet during his rebirth at the cemetery, saying that he didn't look for Voldemort after his downfall because he believed him to be "finished". He begged Voldemort to forgive everyone. Voldemort responded by using the Cruciatus Curse on him and saying he wanted thirteen years repayment before forgiving the Death Eaters for the lack of belief they had in him.
In 1995, Voldemort was seeking a prophecy that had been made about himself and Harry Potter, a record of which was kept in the Department of Mysteries in the Ministry of Magic. Avery told his master that it would be possible to obtain the prophecy by placing Unspeakable Broderick Bode under the Imperius Curse and having him get it for them. This attempt failed, as prophecies are protected by spells that only allow them to be retrieved by the person about whom they are made. Voldemort punished Avery for this mistake.
Battle of the Department of MysteriesEdit
Avery later fought at the Battle of the Department of Mysteries, where he was paired with fellow Death Eater Walden Macnair. Avery was most likely sent to Azkaban along with the other Death Eaters presen tat the battle, save for Bellatrix Lestrange. It is possible that he escaped in 1997, along with the other Death Eaters. It is also possible that Avery fought in several other battles, including the Battle of Hogwarts.
After Lord Voldemort's final defeat, Avery was presumably killed during the Battle of Hogwarts or was sent to Azkaban after the battle.
- Avery, Sr. (possibly)