While the historian initially sought to present a purely _______ account of the monarch's reign, the sheer volume of personal letters and diaries he uncovered made it impossible to ignore the monarch's deeply _______ nature.

✓ Correct Answer: Option A

The historian aimed for an 'objective' (impartial) account but found 'personal letters' revealing an 'idiosyncratic' (distinctive, peculiar) nature, implying a contrast between impersonal history and personal character.