Diesel is, in essence, the average pantomime villain. He is oily, malicious, devious, scheming, and full of ideas to get revenge. It appears Diesel has a good side in him, but one would still have to look deep to find it. He does want to be a really useful engine, however, since his arrival, he has given Diesels a bad reputation. He is also very proud to be the first Diesel on Sodor.