“I didn’t grow up with a younger brother – I have a half-brother but we didn’t grow up
with each other – and my research was to understand what that’s like, and to get into
why Newt doesn’t like him and why they don’t connect. The communication has gone bad.
Theseus is very head-in-the-sand in a sense. He’s blind to what Newt needs, and,
objectively, there’s a selfishness to that and an arrogance to that and a brute force-ness
to that. But subjectively, it’s about protection and it’s about love and it’s about caring.
Theseus is a carer. He’s described as a hugger, and I think he’s trying to hug the whole world.
Newt, in particular. When you aren’t able to give what someone needs, to facilitate what
they need, you then either push them away – which he does – or suffocate. I think the
friction between them is Theseus doesn’t understand what Newt wants, and he is overbearing.
It’s almost like he’s got him in a big, old bear hug and Newt doesn’t want that at all.”

— Callum Turner on Theseus and Newt’s relationship in an interview with ETOnline