History: Modern Day
Scotty was born in central Scotland in 1973; much like his canon-verse counterpart, he studied at the University of Glasgow and graduated with honours. He did his PhD at Oxford Brookes. After graduating, he worked for Lockheed Martin for several years to secure his IMechE accreditation, and was eventually recruited by the European Space Agency. Impressed by his work on scramjets (supersonic compression ram jet engines), they put him in charge of a research group working on suborbital spacecraft.
Unfortunately during preliminary testing, the experimental compressor in the prototype ship shattered, unable to withstand the stress it was operating under. The resulting shrapnel punctured the fuel lines and caused an explosion that destroyed both the ship and the wind tunnel it was being tested in. Scotty and several others present were severely injured, though thankfully there were no fatalities. The project was quietly terminated and its personnel reassigned; Scotty, as the person nominally accountable for the whole mess, was fired.
These days he works on the maintenance crew at a minor airport, mainly just to keep his hand in and earn a bit of money. The vast majority of his time is spent trying to work out what exactly went wrong with the experimental engine and find a way to fix it, still absolutely convinced the technology should work