"All I've done for the time I've been here is shunt. I can do a lot more than that."
Years before he arrived on Sodor, Andy worked for the Diesel Army. He was responsible for the creation of the Fire-arm.
Andy arrived on Sodor during 089 and Toby's abscense. He made a rude first impression however, as he pushed Caitlin and Hiro into the Walney Channel at the Vicarstown Rolling Bridge. Andy eventually made his way to the scrapyard and befriended Diesel 10 and BoCo.
The following day Andy was working at Knapford Harbour, where he was teased by troublesome trucks for resembling Diesel 10. He also met a frontloader with a long name, which Andy nicknamed, Lloyd.
After Knapford Station was destroyed, Andy helped with the rebuilding process. During the process he was assigned to shunt a train for Edward to take to Wellsworth, but Andy managed to convince Sir Stephen Topham Hatt to let him take it to Wellsworth himself. On the way, Andy met Stephen, an old steam engine who he connected with. He later met a truck named Jay, who he also shared a connection with. The were both lonely; Andy because he was a member of the Diesel Army, and Jay because he was left in a siding by Connor. The two became good friends and planned to meet again. After a talk with BoCo, Andy was informed that his controller no longer required him, and Andy was now a permanent member of the North Western Railway. Andy felt more lonely and self conscious than ever.
Andy, while shunting, met a truck named S.C. Ruffey who gave his perspective on things. Ruffey claimed that everything was a lie created by The Ones Who Know, but Andy didn't believe him. That evening, he met up with Jay again, but it turned out to be a trap, and both were captured by the professor. Andy, not knowing who he was or what he should do anymore, turned to the criminals, and joined them on their conquest, after Jay, his only friend, was killed infront of his very eyes.
Andy was repaired by Professor's Gang, and then transported them on a mission to kill Thomas. The mission was a success and the next day, Andy assisted again by transporting incredidite from the docks after it was stolen from Stepney and BoCo by members of the gang. Andy was pursued across the island by BoCo and Sindey, but got away in the end. He delivered a shipment of incredidite to the mainland and later stopped at Barrow-in-Furness for a break and then continued on.
Off-screen, Andy delivered Thomas' body to Timothy. The next day he went to fetch some iron for Professor's Gang, but was interuppted by Diesel 10. The latter wanted to avenge all who were manipulated by Andy before and after the war, but Andy didn't want to hear it. The two fought and Andy won and then escaped. It is currently unknown where he went.
Andy appeared in Ivo Hugh's nightmare, claiming that the latter destroyed his home. Andy then threatened to kill Connor. Ivo charged at him and upon impact, Andy faded into smoke, but his lingering voice told Ivo that they had equally dark pasts.
Andy is a large green diesel engine that arrived from the Mainland to work on Sodor as a replacement for Toby, 089 and Thomas while the three were in different predicaments. Andy is always grumpy and keeps to himself which explains his lack of friends, with the acceptions of Diesel 10 and BoCo. This can be understood as the engines don't really trust diesels after the events of the Locomotive War and Andy is a diesel that secretly served a large role in the war. Being the only surviving diesel from the Diesel Army, Andy is lonely and suffers from depression. He feels that Sir Topham Hatt doesn't let him show off what he can really do, and has a raging temper. All of these factors leave him open to manipulation, specifically by Professor's Gang. He later joined said gang, and is now very loyal to them and helps them with their various schemes.
- Andy's model is Diesel 10 without a claw. This was noted by the troublesome trucks as an inside joke.
- Andy is currently the only surviving member of the Diesel Army.