If ego is still heavily present it will impede the ability to be completely generous. If there is an addiction to alcohol or drugs it will disrupt the ability to bond the cellular bodies. One particularly disruptive force is addiction. If they are not, the interaction can destroy both of them. This means they have done the personal work and be in balance from within. In order for this coupling to work out each of the parties needs to be fully matured in both their male and female sides. If you move into sexuality, your bodies will fit together in a way like no other.
If you touch, there will be an overpowering magnetism. You will have an instant draw to be with this person. Maybe your eyes are not the same color, but there will be an unmistakable physical resemblance. You will recognize the other immediately. There are conditions that must be met before the melding can be successful, otherwise the meeting will create chaos in the lives of each, so much so that it can destroy the lives of one or both. Like an atom splitting, there is massive amount of energy created if the halves are brought back together in fact explosive. Apparently they rarely meet and there is a reason for this.
Twin souls are when a two people come from the same source like a atom splitting. But what of the question of the twin flame? We can marry or have a best friend that is our soul mate. These are the relationships that cause impact and where the equivalent of a lifetime of relationship can happen in a single night. What is the difference between a soul mate and a twin soul? From what I understand, we can have many soul mates, which means we have a soul family that weaves in and out of our many lives, like a dance.