As a hatchling the hound -side is fully in control untill the first soultwin level is reached and the soultwin wakes up for the first time.

Around the age of 4 to 5 months the second level with the soultwin is reached and a battle of dominance over the body starts.

Soultwins joints start to work properly. It gains more of it's own free will and by instinct will first try to dominate the full body. This results to some uncontrollable movements and twitches with the hound. Soultwin starts to grow it's first bones to finalize the attachment to the host.

By the age of 20 - 40

The hound will slowly fade so that the soultwin takes mostly control of the body they share. They still communicate with each other in their minds and soultwin often acts out on their hosts wishes. Eventually while closing to the end the soultwin will be only one left in control of the body since the hounds mind has disappeared and it's only job anymore is to keep the body alive.