Bran the Trojan horse

My theory, whilst not based on much so feel free to add or shred, someone may have posted it previously but it's nowhere I've read. My theory is that Bran is a Trojan horse of sorts. We know that the children of the forest created the Night King and the magic wall keeps them up north and that after Bran being marked by the Night King he passed through the wall. What is odd to me is that the old three eyed raven who lured Bran up north with visions, this old, ancient consciousness, allowed himself to be killed by white walkers when he can warg. I'm thinking that the wall also keeps the children of the forest and the three eyed raven out and after years of being relegated to the north, cut off by the wall, they want to retake westeros from men. So, to do this, the three eyed raven chose a strong green seer vessel and had him come north in order to train his abilities and eventually warg into him. This may explain Brans social awkwardness and odd comments thus far. From there, The three eyed raven in brans body can work at undermining the defenses and assist the army of the dead through the wall as the 'branded' Bran body can now came and go through the wall. Also, if you warg into another green seer, you should continue to be able to ward at will, without being trapped as you could in an animal etc. Just throwing it out there.