>>713216193
Bit like christianity if you think of it. The tree is the Father, Radagon the Son, and Marika the Spirit
Three beings, three faces, one divinity

Certainly it's possible they act as the consciousness of the tree, but I don't think it needs one. Marika can already command it through the connection with it and the Elden Ring. The tree really just served to absorb the honored dead and refine new blessings from them to heal those under it. Our flasks of tears are all that remains of its old bounty

Grace seems controlled by Marika psychologically, so I don't think the tree would be needed for that side of the equation either.
But the Shaman grandmother does point to some merging with the tree, and Marika and Radagon are inside a pillar of light inside the door of the Erdtree, which might imply a spiritual realm of some sort as well