Although Squibs have not been mentioned yet in the Fantastic Beasts film series, the theory that Jacob will turn out to be a Squib in Fantastic Beasts: The Secrets of Dumbledore makes sense. Fantastic Beasts and Where to Find Them introduced audiences to the Wizarding World’s first major Muggle character: Jacob Kowalski. After accidentally switching suitcases with wizard Newt Scamander, Jacob became involved in not only the recovery of missing magic beasts, but saving New York City from a dangerous magical force known as an Obscurus. Once New York was safe though, Jacob’s memory was erased to maintain the secrecy of magic.
Despite this, Jacob has become increasingly involved in magical affairs in later Fantastic Beasts movies. In Fantastic Beasts: The Crimes of Grindelwald, Jacob regained his memories, but few witches and wizards knew he was working with Newt again for most of the movie. By Fantastic Beasts: The Secrets of Dumbledore though, it seems to be common knowledge that Jacob is fully involved with magic. Jacob not only gets to visit Hogwarts and eat in the Great Hall, but is given a wand by Albus Dumbledore.
Related: Fantastic Beasts 3: How Jacob Can Become A Wizard — Theory Explained
However, it is possible that Jacob was never a Muggle. Instead, one theory (via YouTube) pointed out that Fantastic Beasts 3 might reveal that Jacob is a Squib, or a person born without magic despite having at least one magical parent. The Fantastic Beasts series has already hinted at this twist through both Jacob’s ability to see magic and his interactions with magical creatures. In addition, Jacob’s mysterious family history makes it possible for him to be a Squib.
One way that Fantastic Beasts has suggested that Jacob might be a
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