Some people establish their own boundaries, when they walk into a room. Such a person may not be the most successful or the most talented person in the room, but somehow is able to draw a social line with a message that one is advised not to cross. Such a person is not threatening, but rather establishes boundaries through a degree of courteous reserve. One dimension is that such a person is not seeking your friendship, or influence. Another dimension is that such person knows who he or she is and is not, and is quite comfortable with such knowledge.
Friendliness, with a distinct edge. You may need me, but I don’t need you.
A certain form of leadership.