Praiseworthy was a young child part of a crew of human colonists who settled on the planet Gliese 581 D in the far future.
His mother was part of the set-up team who were awoken from stasis before the rest of the colonists to ensure the city was working properly. However, she was killed with the rest of her team when she showed grief over the deaths of her friends and colleagues. Her bones were turned into fertilizer.
The Twelfth Doctor later discovered a pendant she kept with a hologram of Praiseworthy in it and deduced he was her son.
When the Doctor decided to blow up the colony without knowing the other humans were still in stasis, Bill came across Praiseworthy who had just woken up. The Doctor quickly repaired his sabotage and while no one was looking, he went outside to look for his mother. However, he instead encountered an Emoji bot who gave him an emotion badge. When he realized his mother was dead, the Emoji bots seized him and prepared to kill him as he was broke down in tears. He was saved by Steadfast who shot the robots. But this only angered the Vardis into attacking the human crew as they had developed sentience. Bill protected Praiseworthy from their attack. Once the Doctor reset the Vardis' systems and erased their memories of their errors, an Emoji bot offered Praiseworthy a drink to try to cheer him up.(TV: Smile)