We have no clue at all about Bran, the closest thing we know is that there are greenseer humans and greenseer children of the forest. Greenseers are kinda like merlin druids.

We really don't know much about the children of the forest, or greenseers at all. We only know about three powers of the greenseers 1) Ability to warg animals 2) Ability to weirwood trees (possibly other plants), and through weirwoods see the past, present, and future 3) Ability to cause cataclysmic damage to the earth itself separating Westeros from Essos in the past and separating the north from the south and creating the swampy neck.

Now one thing that really is weird to me is how weirwoods are trees but with faces. They have blood sap and white bark similar to how our bones are. Are they just unique trees, or does the connection with bones and blood have some deeper meaning, are they somehow related to blood magic?