One can be doubly sure of one's enemy moments . What about those who masquerade as friends.That's why a famous spiritual guru once said " your friend can do what your enemy cannot do".( An enemy cannot push you to become a drunkard but a friend can do it ) Suppose you are in a possession of a small piece of land in the central part of the ciy. Some hoodlums would pose as friends and play on your weakness . If you do not have one they 'll try to induce one. They always aim for a pound of flesh . In other words, its time to introspect are they fit to be friends? .
One has to be very cautious about "reformed enemy" because one never know when he/she would strike back. Then it becomes prerogative on our part to spy on that personality(ies).