The Thin Controller has three sons and two daughters. Their names are Peter, Paul, Patrick, Pansy, and Penny.
In All the World's a Stage, after the Thin Controller was injured, they, along with their mother, were seen crowding around him as he talked to his engines. However, he was less worried about his injury and more worried about losing credibility with them!
All five of the children are very cheeky, as indicated when the Thin Controller and his engines were putting on a play to satiate The Actor, the Thin Controller mentioned that if the play went wrong, he would lose all credibility with them!
Peter is the eldest at ten years old, and is a young, aspiring athlete. He wears a white, collared shirt and love to play sports and run. Along with his brothers, he loves to roughhouse and get into mischief! He loves hearing Fearless Freddie tell his stories about being the fastest engine in the hills!
Paul is nine years old and is commonly seen with his grey knit cap. He is a bit of prankster and never goes anywhere without his slingshot! Paul is closest with Duncan on the Skarloey line and loves to get up into mischief.
Patrick is eight years old and and is very kind and courteous! He can be indentified by his long hair and red headband. He is Pansy's twin brother, and he is very close with his sister.
Pansy is also eight years old and is very shy, and is well known for the pink flower beret she keeps in her hair at all times. She can play the harmonica very well and is very aware of her surroundings! She loves to listen to Rheneas and Skarloey's stories of the past, and is very close with her father. She is Patrick's twin sister.
Penny is the youngest at seven years old, and is best known for her long brown hair, just like her mother. She is quite beyond her years and is very intelligent, and is not afraid to show it! Being a perfectionist, she enjoys watching Rusty repair the line.
- Season 2: Swan Dive (cameo), All the World's a Stage (do not speak), Swashbuckler (mentioned), Self-Fulfilling Prophecy
They may appear in season 3.