When Bill Clinton was impeached in 1998, the Executive must have put together some plans for the orderly transfer of power — if Clinton had been convicted, Al Gore would have immediately taken over as President. Presumably Gore and pivotal members of the presidential chain of command would have undergone various preparations. Are there responsibilities and secrets that only the President knows about but which the VP would need to have a full command of on taking office? What would it be like to be initiated into these secrets, but then remain the VP as the President is acquitted in impeachment or whatever?
(Yes, perhaps all the succession plans are fully elaborated when P and VP take office, and no further preparations are necessary in view of an impending transitions; perhaps all the P-only secrets and contacts and responsibilities are revealed to the successor only after succession is a sure thing; etc. Still it seems that there might be some interesting middle ground.)