Percy is a cheeky saddletank who was brought to Sodor to help run the railway during the big engines' strike.
Percy was probably built by Avonside and went gone through a subsequent rebuild in the years preceding his second-hand sale to the North Western Railway. He is said to have been found wearing Hunslet parts, according to workers at Crovan's Gate.
When Gordon, James, and Henry went on strike in protest of the extra work they had to do since Thomas left to run his branch line, the Fat Controller decided that the railway needed another tank engine. Going to the engine workshop, the Fat Controller saw a green saddletank and when the engine confirmed he was willing to work hard, the Fat Controller bought him and named him Percy. Bringing him back to Sodor, Percy was charged with running the branch line while Thomas ran the Main Line with Edward and was allowed to stay after the big engines surrendered. At first, Percy liked to annoy the big engines. Percy was later waiting at Tidmouth, but forgot to whistle to the signalman, and thus was startled when Gordon came running towards him with the express. Gordon managed to stop in time, but Percy was so frightened, he ran away, and ended up in a sandbank. He was rescued by Gordon and took up the duty of station pilot at Tidmouth.
Percy was still a cheeky engine and often liked to play jokes on Gordon and James, but one day the other engines got their revenge when Percy failed to recognise a "backing signal". After this, Percy was subject to bullying from the big engines until Duck arrived and helped Percy to put the big engines in their place.
As the television series has progressed, Percy has been dumbed-down in order to teach viewers difficult words: he would say "dingy-fried" where anyone else would say "dignified". He is also shown to make obvious mistakes.
Percy is incredibly accident-prone and holds the dubious record of the most accidents in one season - five, in the second season - crashing into some buffers, falling into the sea, being pushed onto a brakevan, colliding with a cart, and being hit by a falling crate of treacle. So far, his silliest accident yet was in the sixth season,when he slipped on oily rails, crashed through the chocolate factory, and emerged covered in chocolate.
Since the second season, Percy has had a small rivalry with Harold, stemming from their race. However, they are always willing to help each other when in trouble.
Percy is primarily based on an Avonside 0-4-0ST with the body of GWR 1340 Trojan, the bunker of GWR 1361, Hunslet underframes and valve gear, a smokebox protruding from his saddletank, external cylinders and motion, and sandboxes underneath the tanks on his footplate.
Modifications made to Percy's shape include the angled smokebox supports and the cab being cut down slightly from the back for the bunker.
Percy is painted NWR green with NWR red-and-yellow lining and a "6" painted on his bunker sides in yellow.
In the Railway Series, he carries two builder's plates, one on either side of his cab.
The Reverend W. Awdry and C. Reginald Dalby did not get along very well. Awdry considered Dalby's drawings "toy-like"; this relationship was worsened by the creation of Percy, who was depicted as an Avonside 0-4-0ST/GWR 1340 Trojan with a bunker.
When Percy the Small Engine was published, Awdry wrote to Dalby, criticising his illustrations and claiming Percy resembled "a green caterpillar with red stripes". This was too much for Dalby and he promptly resigned. However, the insult was not forgotten: Thomas called Percy "a green caterpillar with red stripes" in Tramway Engines.
It is debated as to what year Percy arrived. The Island of Sodor: Its People, History and Railways states that Percy came to Sodor in June 1949. However, Henry is said to have been rebuilt in 1935 and Percy makes several appearances in the presence of the pre-rebuild Henry, suggesting that either Henry was rebuilt later on or that Percy arrived before 1935. A post on SiF states that Christopher Awdry affirms the arrival date in The Island of Sodor: Its People, History and Railways to be incorrect and that Percy came to Sodor before 1935.
- Percy' large scale model used for the spin-off series, The Pack is currently on display in Japan at Thomas Land.
- In Jack and the Sodor Construction Company, Percy's dome is green and the steps up to his foot plate are red.
- Percy was the first character to have merchandise.
- Since the fifth season, Percy has had a permanent lamp.
- One of Percy's models is currently on display in Canada at Nitrogen Studios.
- In the French version of the Classic Series, Percy was called Pierre, but during the New Series, he is called Percy.
- From the eighth through twelfth seasons, Percy's cab windows were blacked out.
- "Do you know what?" asked Percy.
- "What?" grunted Gordon.
- "Do you know what?"
- "Silly," said Gordon crossly, "Of course I don't know what, if you don't tell me what 'what' is."
- A conversation between Percy and Gordon, "Percy the Small Engine"
- "Nobody listens to me now! They think i'm a silly little engine, and order me about. I'll show them."
- Percy, "Percy the Small Engine"
- "Wheeeeeeeeeeesh!" Percy gave his ghostly whistle. "Don't be frightened, Thomas," he laughed, "it's only me!"
- "Your ugly fizz is enough to frighten anyone," said Thomas crossly. "You're like - "
- "Ugly indeed! I'm - "
- "A green caterpillar with red stripes," continued Thomas firmly. "You crawl like one too."
- "I don't."
- "Who's been late every afternoon this week?"
- "It's the hay."
- "I can't help that," said Thomas. "Time's time, and the Fat Controller relies on me to keep it. I can't if you crawl in the hay till all hours."
- An argument between Percy and Thomas, Tramway Engines
- "I can't see any," said Percy. "Where are they?"
- "Any what?" said Gordon.
- "Ideas above the station - the sky's empty."
- "Like your smokebox, Percy!" laughed James.