Soulmates are something the Wizarding world holds dear to their beliefs and traditions. When your twelfth birthday appears the name of your soulmate or soulmates mark will appear on either one or both ankles. If you have a Dominant mate(s) the name(s) will appear on your right ankle. If you have a Submissive mate(s) the name(s) will appear on the left ankle.

(Harry will have two names on his right ankle. Fleur has Bills on her right and will have Harrys on her left. Bill will have two names on his left.)

Everyone has four chances to a mate. If your mate rejects you it can take up to four years for a new name to appear. If the fourth chance at a mate rejects you (rare) a thin black line will appear around both ankles. If the bond is complete the names will move from the ankles to the wrists. (With the same left and right concept)

If a two people are already mated and don't have a third name then the only way they will get a third name is if the third name is on their last chance at a mate.