Talk:Arthur Pendragon/@comment-5494183-20160101233545/@comment-5105486-20170320180417

You kinda answered your question already. "Vision" allowed Baltra to know Arthurs last name (Pendragon) even though he was living with his adoptive father and brother at the time, thus he knew that Arthur was actually the biological son of Uther Pendragon. That's it.