I'm pretty sure we all know I'm obsessed with Marauders fanfiction. That's my only reason for making this post.
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We know that Alice comes from a pureblood family. We know the 'Sacred Twenty-Eight' is a group of pureblood families, and that is where I am basing some of my reasoning.
With logic, we know that Alice could not have been a Black or a Potter. Their family trees are very widely known and we know she is not included in those family trees.
Alice could not have been a Longbottom because then she would have had the same last name as her husband, Frank.
She is not a Gaunt because their family line is extinct, nor an Olivander because even though they are part of the Sacred Twenty-Eight, they technically aren't a pureblood family anymore.
It makes sense that Alice does not belong to a traditionally Slytherin family, heavily elitist and prejudiced families that support Voldemort, so this disqualifies her from being a Malfoy, Crabbe, Goyle, Mucibler, Rosier, or any similar family.
There is a slim possibility that Alice was part of the Greengrass family. We know Astoria and Daphne were raised to believe in traditional Slytherin family beliefs, so it is not a very good prediction.
Some people think Alice could have been part of the Weasley family, but their family is too widely known thought the series and is too famous for us to never hear of Alice being a member.
Alice probably wouldn't have been a Prewett. We all know that Molly Weasley's maiden name is Prewett, and her brothers were Fabian and Gideon Prewett. It wouldn't have made sense because Alice would have been her sister or a close cousin. Therefore, Molly would have known about Neville and it would make sense if her children knew about Neville too. So, we know Prewett would not have worked. Of course, there could have been miscommunication which could be the reason why Molly didn't know that Neville was her nephew (if Alice & Molly were sisters). If this theory is correct, it would probably be the fault of miscommunication.
One person thinks Alice could have been a Selwyn and not Fortescue. The Selwyn family is something we don't see much in the books. We know Umbridge used their family as an excuse when questioned about the Slytherin locket, but besides that, we don't know much about the family. Their family is part of the Sacred Twenty-Eight. We know there is a Death Eater with the surname Selwyn that participated in the Second War. Although there is one known Death Eater from their family, it doesn't mean their whole family is made of Death Eaters. I disagree with this theory, but there's a possibility that this theory is correct.
According to the Madam Pince Tumblr page, there's a possibility that Alice is part of the Lestrange Family. She could be a second or third cousin of Rodolphus or Rabastan. I'm sure that Alice is not their sister. If this is true, she would be distantly related to the Black family because of Rodolphus's marriage to Bellatrix Black. It would make sense why Bellatrix and the other Death Eaters would be prejudiced against Alice and her family. The Longbottoms disagreed with Voldemort, thus making them a target for the Death Eaters who deemed them as 'Blood Traitors'.
Many fans insist that her last name is Fortescue, but nobody seems to know where this came from. This would make her, if not closely, related to Florean Fortescue, a descendant from the once Hogwarts Headmaster, Dexter Fortescue. Again, this information is not confirmed. But we do know about Harry's encounter with Florean. He sounds like a pretty cool guy. What makes me confused is why he isn't known by Neville. We can assume that if Alice was part of the Fortescue family, she'd be Florean's sister or a close cousin since they are alive at relatively the same time. So why isn't he 'in' Neville's life? I'll leave that for you guys to think about.
Using this information, I can predict that she could have been a member of the Fortescue or Prewett families, but of course, this is not confirmed. Let me know your thoughts!!!
Inspired by: https://harrypotter.fandom.com/f/p/4400000000003422138
