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 basketball. (TV: Spyfall)
Over a period of months, Tibo began to feel more anxious, being paralysed for long periods of time. He tried to cope by having human contact by talking to cashiers in shops, but only found self-service checkouts. In the latter few nights, Tibo was tormented in his nightmares by Zellin.
When Ryan returned from his travels, he visited Tibo and brought chips with him. He noticed Tibo's different behaviour, and over a game of FIFA, Tibo admitted he had been finding his life difficult, and also mentioned his Zellin induced nightmares. That night, Zellin kidnapped Tibo when Ryan stayed over.
He eventually was rescued by the Doctor and the rest of the TARDIS team, discovering Ryan was a time traveller, and returned to his own time. Having discovered the truth about Ryan, he asked him to come back soon. In return, Ryan convinced him to go to group therapy. (TV: Can You Hear Me?)