Bert (Diesel)

History
In their first appearance, 'Arry and Bert approached Stepney, who had been sent to the smelters by mistake. They shunted Stepney into the larger smelting shed underneath a giant grabber and threatened to scrap him. Thankfully, Stepney was saved by the Fat Controller, once 'Arry and Bert left.

'Arry and Bert are known for playing tricks on steamies, such as making them "middle engines". Once, they shunted trucks in front and behind Percy. This later led Percy to being pushed onto the coal tipper by mistake. Later, 'Arry and Bert played the same trick on James.

Sometime later, 'Arry and Bert frightened Fergus away from the smelters and bullied Neville when he first arrived on the Island of Sodor.

On some occasions, 'Arry and Bert's teasing ways backfire. Once, they played a prank on Thomas and Emily during Halloween, though they ran away when they thought Emily was a ghost. Another time, 'Arry and Bert teased Percy for having a whistle. Percy paid them back by creeping up behind them and blowing his whistle. Later, along with Diesel, 'Arry and Bert began teasing Thomas for being smelly, but were later covered in stinky cheese and rushed to the washdown.

'Arry and Bert were part of the group of diesels that took over the Steamworks.

'Arry and Bert teased Henry because of his need for special coal, calling him "Mr. Special Steam". They also laughed at Gordon after he ran into Diesel's flatbed and damaged his bufferbeam.

'Arry and Bert like being rough and tough along with Diesel, they realised Diesel was trying to be nice to everyone. So Thomas took 'Arry and Bert to the ducklings while Diesel followed behind them. Diesel, 'Arry and Bert then said that the ducklings were cute.