Dan A left GMC over a dispute with CEO Mary B over direction of GM Cruise ( aka Mr. Dan wanted to replace Mary Barra as new CEO of GMC).
He hasnt joined Exxon so he can be the "President" or "SVP"... it is very very clear that hes gunning for the top job. I have a feeling that Bart C was on track to be groomed to be the new President/SVP and eventually the CEO; but in 2023 due to David Scotts fiasco Bart was taken off his development path.
There is no way Dan A is gonna let Bart surpass him UNLESS Darren personally is impressed by him.