T.C. sell off their flights from Aberdeen to Pegasus and Freebird. So when people book with T.C. They do not mention this fact. The only way to know for the novice is when they try to book seats together, meals etc., To the initiated we know by the flight number when it changes from TC.
However, the Turkish Airlines used are much better than T.C. nicer staff, good planes, more legroom and no hard sell every two minutes. It makes the flights much more pleasant.