For those who prefer to isolate their partner from others in a relationship, there are many indicators they find will help them with their goal. They do not seek out the most popular person in a group because they would tend to be difficult to isolate, so they are often looking for someone who is quiet and shy. The person who does not expect a great deal of attention is often one who needs it the most, so someone seeking a malleable partner will often use that need to accomplish their own goals.
A lack of attention from others is often a sign that a person is lonely, and being given attention from a new person will make them vulnerable. Their life could already consist of a great deal of isolation, so the person who dates them will be the center of their attention. This works in favor of the person who seeks a partner they can keep away from others, so they are ready to pounce as soon as they meet the perfect candidate.
While many cases of isolation are subtle and take time, a person who has found someone already suffering from a lack of social contacts can do their work quickly. It will only take a few months before they can exercise almost complete control over their new partner, and they will be able to control them with little further effort. Their work has mostly been done for them, so they can enjoy the rewards sooner.
People who isolate their partners often find they become bored with them shortly after they have achieved their goal, so many of them are already looking for someone new within a matter of months. They will enjoy the benefits of their handiwork for a while, but they will eventually leave the other person in a state of devastation when they move on to their next challenge.