Donald and Douglas are two Scottish twins from The Island of Sodor.
Donald and Douglas are practical, peppery, proud and level-minded. Donald and Douglas are strong and very able when it comes to doing any job. They are fully capable of being firm with the other big engines, such as Gordon and Henry and the troublesome trucks. They are also used to clear snow in the winter coupled to both ends of a breakdown coach with a snowplow at the front of them. They are also very cheeky, not nearly as cheeky as Bill and Ben though, they can usually be found cracking a joke at the other engines when they get karma. Between the two, Donald tends to be the charming, witty joker whereas Douglas is the smart, quick-thinking, calmer-natured one of the pair.
Donald and Douglas may have the occasional arguement with each other but at the end of the day, they know that they are nothing without each other. They also used to have a strong dislike of diesels. But over time their dislike has softened due to working with the kinder of Sodor's diesels such as Salty.
Donald and Douglas are both based on the Caledonian Railway McIntosh 812 Class 0-6-0 goods engine. Their numbers, however, would realistically place them in the 652 sub-class. One example survives in preservation.
Donald and Douglas were painted BR black goods livery with red-and-white lining on their tenders and yellow numbers with red outlines.