Bran's last chapter in ADwD is full of little treasures that are easy to overlook at first or second reading.
When Leaf was asked about her speaking the Common Tongue she said
According to her statement, two conclusions can be drawn:
She learned the common tongue specifically for Bran, &
she knew about Bran for at least 200 years.
Even if we disregard this statement completely, the following quote by Bloodraven confirms the theory that Bran's arrival was anticipated
This indicates that Bloodraven has been waiting for Bran since, at least, Eddard's birth, i.e., 35 years ago.
Another significant point is the hidden greenseers that Bran sees when he goes exploring deep into places that Leaf explicitly warned him not to explore.
And when he does wander, this is what he finds
Yet they refer to Bloodraven as the last greenseer.
The only explanation I find for this discrepancy is that, perhaps, it's to convince Bran that the survival of the human race depends on him completely in an attempt to prevent him from leaving.
There are many hints in the book that Bran was not the only person approached by the greenseers of the CotF's godhood.
First Bran's first falling dream:
We can perhaps conclude that those bones are the result of failed attempts to awaken the third eye of those now deceased.
Another interesting observation it seems that only after a near-death experience that those chosen are first approached.
It seems also highly probably that Patchface was also approached by Bloodraven when he drowned in the sea, which explains some of his strange statements. Under the sea seems to be a reference to his near-death experience because that is where he actually was when he experienced those dreams/visions.
I think this is a reference to Bloodraven appearing to him as a fish as opposed to crow, since he's experiencing those dreams/visions in the sea.
Remember the description of the CotF's cave
There's also the many associations of death and blood with the CotF and their weirwoods, such as this quote from Jon's dream
I'm not convinced yet that the CotF have an evil agenda, but I do believe there's more to them than they openly reveal to Bran, and, therefore, the reader. It seems highly unlikely that they are merely pacifist creatures resigned to their eventual doom in the world that men have made and are simply working diligently to help humanity at their own expense. This is not what would be expected of GRRM.