User blog comment:The Dragon Demands/Season 5 trailer officially released/@comment-1600847-20150130164618/@comment-3968559-20150202162258

But IF Aemon the Dragonknight was really that one Targaryen's father, then the Blackfyre line is the legitimate one, what would make Aegon's claim stronger than Dany's. Note, that I don't think Jon is the heir even if R+L=J is true.