Rudolph Diesel was the inventor of the diesel locomotive. He was a shrewd businessman, stopping at nothing to make sure his diesels are proven superior.
During the 1890s, Diesel and William Meisner came to Sodor with the intention of building a railway on the Island. Initially, Diesel was to provide the engines for the line and Bill would fund the project. However, after Sir Nigel Gresley becomes involved in the project, the plans quickly change and Diesel is shafted in favor of a collaboration between Meisner and Sir Nigel Gresley. This betrayal caused a great deal of bitterness on Diesel's part, and in turn fueled his drive to implement diesels onto the island.
Season 1 Edit
Rudolph first appears in Tensions Emerge, in which he tries to sell Sir Topham Hatt more diesel locomotives. He fails to convince Sir Topham, and leaves to wait for his train. upon waiting, he witnessed a flaming coal truck shoot from the Skarloey Railway Tunnel. Upon the arrival of the Duke and Duchess of Boxford, Mr, Diesel sabatogues some track near the Skarloey Railway. Upon hearing Spencer approaching, he draws back into the bushses to spectate. His manipulation manages to derail Spencer, leaving the Duke and Duchess quite confused. During this confusion, Diesel apporaches the Duke, chastisting steam engines and offering him a diesel for sale. The Duke and Duchess decide to make the purchase.
After the sale, Diesel goes to Hatt to gloat about it and try to convince Hatt to buy more diesels again. After being denied, Rudolph threatens to change Hatt's mind before recieving a call from the Duke and Duchess. Their new diesel has broken down. He attempts to smooth things over, but he ultimately takes the Diesel back, sending him to be repaired at the Diesel Works.
Season 2 Edit
After Sir Topham Hatt's death, Rudolph Diesel returns and is able to strike a deal with Alfred Herman, bringing many of his diesels to Sodor. In Authority, he was revealed to be Mr. M, the mysertious figure behind all the bombings and negative occurances on Sodor in summer of 1945.
Season 3 Edit
After discovering a set of plans amongst the late Sir Topham Hatt's belongings, Phil Aardman secretly summons Diesel back to Sodor to discuss them. The plans are revealed to be that of a hybrid Steam-Diesel engine, a compromise Diesel devised during his involvement in the development of the North Western Railway. After Diesel is cut from the project however, he is forced to scrap his plans and pursue a different route. Phil manages to convince Diesel to construct the engine for him. However, as the project neared completion, Stephen Hatt framed Phil of constructing a doomsday device, which put the project on hold after Phil's arrest. After Phil returns to Sodor and clears his name, he and Diesel complete the project. Once the locomotive is completed, Diesel requests the engine be named William. Following this, Diesel returned to jail, where he passed away three days later.
- Season 1: Tensions Emerge, Duke & Duchess, Revolutionary, The Blockade Committee, Hatt (does not speak)
- Season 2: Consequences, Reform, Day of the Diesels, Phil (masked), Authority
- Season 3: Inheritance Parts 3, 4 and 7
- Season 4B: Best Laid Schemes (flashback)