Mason (Rosa)

Mason was a police officer from Montgomery, Alabama in 1955.

He visited the Thirteenth Doctor, Graham O'Brien, Ryan Sinclair and Yasmin Khan's room at the Sahara Springs Motel. Mason had been told by the town racists that Team TARDIS had been stirring up trouble (as they had constantly come to the defence of Ryan) due to them exaggerating things. Because the Doctor and Graham had been seen with a African-American boy and "Mexican' girl, he reminded them that it was a criminal offence to harbour non-white individuals on segregated premises, before checking the bathroom for Ryan and Yasmin.

When he asked the Doctor and Graham what they were doing in Montgomery, they explained that they were there to pitch the new invention, a smart phone. He said it sounded ridiculous. After he couldn’t find Ryan or Yasmin, he left. (TV: Rosa)

Personality
Aside from a law-abiding man, Mason appeared to be stern and aggressive. He invited himself into the hotel room without proper procedure, and got in Graham's face to intimidate him. Despite the fact the Doctor and Graham were polite to him, he nonetheless remained gruff.

Aside from that, he didn't escalate things and was only trying to uphold the law; a small shred of decency. (TV: Rosa)