Tibo

Tibo was one of Ryan Sinclair's mates from Sheffield.

Despite Ryan's long absences supposedly being illness related, Tibo began to get suspicious that Ryan was up to something else. Some of these suspicions were confirmed one day when men in dark suits turned up to collect Ryan while he and Tibo were playing football. (TV: Spyfall)

When Ryan returned after a period of time in the TARDIS, he visited Tibo and brought chips with him. He found that Tibo was acting strange and differently than he had been before. It turned out that Tibo was being tormented in his nightmares by Zellin, who eventually kidnapped Tibo the night Ryan stayed over.

He eventually was rescued by the Doctor and the rest of the TARDIS team and returned to his own time. (TV: Can You Hear Me?)

Alternate timeline
After being kidnapped by Zellin, Tibo appeared to Ryan in a nightmare, but he appeared old and was standing on a burning fiery Earth along with some Dregs. (TV: Can You Hear Me?)