Who is Bloodraven? What role has he and will he play in the books

Three-Eyed Raven, Wiki of Westeros

I have my own ghosts, Bran. A brother that I loved, a brother that I hated, a woman I desired. Through the trees, I see them still, but no word of mine

Blood Raven Librarian , L J Koh : r/ImaginaryWarhammer

Bran's Ending In Game Of Thrones' Finale Might Make More Sense In The Books - GameSpot

Bloodraven: The Ultimate Player – part one –

Brynden Rivers (Bloodraven) as the Lord Commander of the Night's Watch, by Charin Makkawiman : r/ImaginaryWesteros

Bloodraven: Part 1

Game of Thrones' Casts Bloodraven Role: Report

Bloodraven and Egg by Gary Gianni : r/ImaginaryWesteros