For example:
How much port did Pitt the Younger drink when Prime Minister?
From the age of 14, he drank a bottle of port before breakfast, a second bottle before tea and a third before supper. His father was a manic depressive and it’s recently been suggested that this high level of consumption was partly to offset a strong case of clinically significant social anxiety beyond mere shyness. On one occasion, a drunken Pitt, overcome from a day’s drinking, was alleged to have vomited behind the Speaker’s Chair; in 1800 he suffered a nervous breakdown and died six years later, aged only 46.
This is only a small part of this historical character’s personality but it’s immediately apparent that this information would be invaluable to a scriptwriter or actor. After all, he could rarely have been sober which would have had both physical and psychological implications.