Yoga legends have it that Patanjali, the creator of the Yoga Sutras, is an avatar of Adisesh. I believe, all of us are. The lord is in all of us - he is the essence of all of us. Thirumoolar brilliantly expounded this in the tamil equivalent of Yoga sutras, thirumandiram as
உடம்பினுள் உத்தமன் கோயில் கொண்டானென்று
உடம்பினை யானிருந் தோம்புகின்றேனே
Because the lord has his temple in my body
I salute my body!
When faced with the tough task of staying afloat in the sea that this world is, dangerous and with fluctuating fortunes, we many times lose touch with the reality of who we really are and we manifest it in the form of suffering - of us and others. This is tantamount to disturbing the lord within. Keeping the lord within in perfect peace and letting him sleep can happen only when we are stable and comfortable. This will in turn let us face the external realities with ease. This is captured beautifully by Patanjali as 'sthira sukham asanam' i.e., asana is when it is stable and comfortable. That is indeed the posture of adisesh - stable and comfortable so as to stay afloat in the sea and let the lord within sleep in peace!
Many great masters in the Hindu culture are called incarnations of Adisesh for the reason that they have realized this great truth. Many of us are yet to do so!
PS: This is my own explanation and it was inspired by the explanation given in class. The discussion in class was on Vyasas commentaries on Yoga Sutras.