From Variety:

“Pretty much in ways that I fully 100% endorse and love, that character is a Robert Pattinson creation,” the film’s director, David Michôd, said on this week’s episode of Variety and iHeart’s “The Big Ticket” podcast. “A lot it was kept under wraps.”

Michôd continued, “The great fear always is that you end up with ‘Monty Python and the Holy Grail’ and ridiculous French accents. But at the same time, I kind of needed his character to be kind of absurd.”

…

“His whole purpose is to be a jerk and to just torment Timmy,” Michôd said. “So I kind of needed him to be a larger-than-life jerk. He needed to be ridiculous. He needed not to have a lot of substance underneath him. He’s just there to annoy.”