Arry and Bert

Arry and Bert are twin diesel engines in Thomas & Friends who work at the Sodor Ironworks.

Bad Qualities

 * 1) In their first appearance, they literally tried to scrap Stepney and were not caught. How worse can they get?!
 * 2) While they were portrayed as menacing villains when they debuted in season 5, from season 6 onwards, they were reduced to just regular school bullies, a primary example being the infamous season 6 episode "Middle Engine".
 * 3) They were at their absolute worst in Calling All Engines!, as they caused so much trouble that they nearly caused the summer to be ruined, and they acted like jerks.
 * 4) Most of the time, they don't receive any consequences for their bad behavior, making them Karma Houdinis.
 * 5) Since they're nothing more than stereotypical bullied and all they do is stand around not doing a lot, they barely have any interesting characteristics to them.

Good Qualities

 * 1) They did end up paying for their bad behavior in "Percy's New Whistle", "Halloween", and "Thomas and the Stinky Cheese".
 * 2) At least they're intentionally portrayed as antagonists for the most part.
 * 3) Sometimes, they can do good things, and there are times where they redeem themselves, just like Diesel.
 * 4) Like most of the engines, their designs are neat and fitting.
 * 5) Kerry Shale and William Hope both do a good job voicing them.