Boco being checked for faults.
BR's dieselisation program is starting to take effect as a number of prototypes are trialed on Sodor.This episode contains the following tropes:
- Adaptational Heroism: Diesel 10, here called Joshua, shows more of the good side that's rarely shown in canon. Sealing it is the fact he doesn't have Pinchy.
- Adaptational Jerkass: Downplayed with Boco, who does act a bit standoffish when meeting Bill, Ben, and Edward, and when Donald takes too long to live up to his promise to bring some workmen, he thinks the Caledonian was trying to humiliate him. That said, when he does learn that Donald's words were genuine, he does apologize to the three.
- Clingy Jealous Girl: Kate, upon hearing that Thomas slept in the same shed as Samantha. She thinks Thomas is cheating on her, but Samantha reiterates that there is nothing going on between them; this devolves into a shouting match broken up by Joshua.
- This also serves as a Call-Back to a shot in "Mountain" where Thomas and Samantha are talking at the coal mine, and Kate shoots a Death Glare at the latter.
- Laser-Guided Karma: Joshua exerts himself by going too fast during his shunting work and overtaxing his engine. Following his argument with James, he proudly boats to James to watch his prowess... only for engine to sputter and die.James: Yes, very impressive!Joshua: Shut up!
- My God, What Have I Done?: Joshua gets this when he realizes his final firing insult struck everyone hard, due to it being how Adam died. He apologizes the first moment he comes out of the works.
- "No. Just… No" Reaction: Implied by Gordon, Henry and James' silent glares at Reginald when he chimes in on their "Disgraceful, Disgusting, Despicable" Running Gag.
- Suicide Dare: Angered by the others teasing him, Joshua snaps at the other engines to go for a final firing. When Mickey finds out, he tears a strip off of him and tells him about Adam, making the diesel realize just how insensitive he was being.
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Recycled Script: "The Diseasel" is downplayed with the title being that Bill misunderstands his driver and that Boco never did take their trucks, they were just yanking his coupling.
