We have two cats, and nothing against Clementine, but Duke is just much more of a buddy to Will. Probably because while he's the friendlier of the two cats (usually), he's also stupider, so Will can play with/tease him longer before he gives up; and lazier, so if he happens to be located somewhere Will wants to play, he's less likely to run away.
Anyway, we have leashes for the cats which we put on them when we let them outside sometimes - we don't tie up the other end, but when they have the harness on it seems to have a psychological effect and they never try to probe the fence for escape routes like they normally do. Will found Duke's leash one day and discovered that when he runs with it, Duke likes to chase it. So Will and "Deekdee" have a new game.