They are attracted by their intimacy, closeness, kindness, and mutual affection. They can give themselves a lot of attention, love, share all their thoughts and secrets, and can create a very melting climate in their relationship. They admire their altruism towards each other and can support each other very much.
It's a very rare combination, because 2s like to take care of others, and can have a lot of trouble letting them be cared of, the same way as they would take care of someone else. They may have problems setting limits, and to tend to depersonalize themselves, or getting lost in each other. In difficult times, the relationship can become very unhealthy, one accusing the other of being too intrusive, or too careless.