In Harry Potter and the Half Blood Prince when Harry and Dumbledore are in Slughorn's memory they see see Tom Riddle with a bunch of other students in Slughorn's office. Among them are Lestrange and Avery:
'Good gracious, is it that time already? You'd better get going, boys, or we'll all be in trouble. Lestrange, I want your essay by tomorrow or it's detention. Same goes for you, Avery.'
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In Harry Potter and the Deathly Hallows when Harry is in Snape's Memory he sees a conversation between Lily and Snape where Lily mentions an Avery:
'...thought we were supposed to be friends?' Snape was saying. 'Best friends?'
'We are, Sev, but I don't like some of the people you're hanging around with! I'm sorry, but I detest Avery and Mulciber!...'
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Tom Riddle and Severus Snape are not in Hogwarts at the same time so my guess is that the second Avery is a son or some relative of the first. Is that right?
