What I’ve noticed about Drift is that he has a tendency to change himself for the people around him, for the bots that he loves. Drift changed himself for the people he loved.
He changed himself when meeting Gasket and became better. He then changed himself afterwards by becoming a Decepticon when Gasket was killed, a death that would drive him to hate. He then changed himself again for Wing and became an Autobot after Wing was killed, a death that would drive him to do good, to be better.
Gasket was the only support system Drift really ever had, so his death drove him to join the Decepticons because he felt he had nothing left. When Wing was killed, Drift had a better control over his emotions from Wings teachings, and he had a better support system, knowing that he had people he could turn to (that Dai Atlas then strengthened). Wing taught him to do good, so Drift followed his promise and became an Autobot instead.
I think a lot of his core decisions and how he chooses to be is by the influence and actions of those around him. Pivotal moments of his life were because of those he loved, moments where he changed himself were from those he loved.