Like the individual atop them, feet have to do some searching for compatible others.
One theory says that a compatible foot to another foot is one which is not too rough or calloused. Trimmed toenails are also very important, as you wouldn't want to pierce your new friend on saying hello.
Feet as friends must be able to stand next to each other and support
one another. It is possible for one foot to anticipate another
foot's needs (not its mate's but another foot entirely) without
touching the other foot.
This, however, is a two-way street. The
feet must be open with one another, and with themselves. The most
intuitive foot can only see as far as another foot allows.
Catts and feet have a special relationship. Many a scar and a scream has come from a catt/foot first date.