The 48 Laws of Power · law 2 of 48
2. Never Put Too Much Trust in Friends — Learn to Use Enemies
discernment
The principle
Friends are quicker to envy you than strangers; a former enemy, given a chance, will work harder than any friend.
The application
Friends accept your rise on emotional terms — and resent it on the same terms. A former enemy you elevate has only your patronage to lean on, and so will guard your interest more carefully than your warmest ally. The lesson is not cynicism but precision: hire on merit and motive, not on affection.
The defensive tell — how to spot it being run on you
If a friend lobbies hard to be hired under you, especially into a role they are slightly underqualified for, the affection is doing work you have not asked of it. Hire them and you owe them; do not hire them and you lose them. Either way, the friendship pays the bill.