Having read all seven Harry Potter books, and knowing the full significance of Fantastic Beasts and Where To Find Them as a child, it's hard to believe Newt used to be the lesser-known Scamander. Unfortunately, the Wizarding World is full of unrecognized prodigies -- underdogs whose achievements are often overshadowed by more charismatic friends and siblings -- and Newt wasn't any different.
Enter Theseus, Newt's very own Percy Weasley.
In 1926, Theseus (played in Fantastic Beasts: The Crimes of Grindelwald by Callum Turner) was understandably the more famous Scamander. Like his younger brother Newton, he probably studied at Hogwarts, but instead of illegally housing monsters and settling for a corner cubicle, Theseus grew to become a war hero, fighting valiantly alongside Muggles and wizards alike during World War I.
From 1912 to 1923, magical folk in Britain were discouraged by then-Minister for Magic Archer Evermonde from aiding Muggles during the war, but Theseus was among those that openly resisted. This led to Evermonde's sacking at the end of World War I, and to Theseus's subsequent rise in the Ministry as the head of the Auror Office. The first Fantastic Beasts describes Theseus as a commanding force in the Ministry, and one of the most powerful Aurors of his time.
In fact, when Newt appeared in the Magical Congress of the United States of America President Seraphina Picquery's chambers shortly after Senator Shaw's death, the meeting participants immediately mistook him for Theseus, who was then better known.
Being Head Auror, Theseus Scamander openly corresponded with Percival Graves, who was then Director of Magical Security and head of MACUSA's Department of Magical Law Enforcement (effectively Head Auror himself, but of his own region). They discussed the recent disturbances presently plaguing New York and whether magical creatures might be involved.
It is unknown if Theseus had spoken to Graves before Grindelwald assumed his identity, or if he had known him much longer. If he had been speaking to Grindelwald all along, it's safe to say that he too, like the rest of the MACUSA, probably didn't notice the difference.
Theseus is said to have a relatively good relationship with his brother Newt. He doesn't think highly of his brother's career choices, but cares for him regardless. LEGO Dimensions reveals Theseus and Newt had corresponded by post shortly before the latter's arrival in New York. In the letter, Theseus talked about problems back home and how he had been sent by the Ministry to retrieve Grindelwald -- and possibly kill him.
Despite the danger it posed, Theseus sounded extremely elated to have been chosen for the job, as well as proud of how far he'd come as an Auror. Judging by how Theseus ended his letter ("wishing you well... wherever you are... whatever beastly quests you are undertaking"), it's safe to say Newt and his older brother probably talk a great deal, even through their differences.
It's worth remembering that Theseus Scamander is also Leta Lestrange's fiancé -- Leta being Newt's best friend and Hogwarts sweetheart. This might have caused friction between the brothers, something worth noting when Theseus and Newt reunite in Fantastic Beasts 2 to take down Gellert Grindelwald. Leta also makes an appearance in the sequel and will likely play a pivotal role.
As an author and magizoologist, Newt Scamander has a nearly hundred-year legacy, while his siblings, including Theseus, have disappeared in the pages of Wizarding history. Still, it's always worth remembering the older brother who might have helped build Newt up and made him the magical tour de force he is today. There's not much we know about the elder Scamander, but what we do know so far is promising.
Directed by Potter film alum David Yates, Fantastic Beasts: The Crimes of Grindelwald is the second installment in the Fantastic Beasts franchise. It stars Katherine Waterston, Dan Fogler, Alison Sudol, Ezra Miller, Zoë Kravitz, Claudia Kim, William Nadylam, Kevin Guthrie, Jude Law, Johnny Depp, Eddie Redmayne and Callum Turner. The film hits theaters on Nov. 16.