What of the guys? There are a bunch of male Vampire Lords in Castle Volkihar but no mention of how they become vampires. The wiki states that Vampire Lords are generally pure-blood vampires but the only mentioned way of becoming one is the "offering" to Molag Bal and I can't imagine Lord Harkon being "offered" to Bal.Moreover if Vampire Lords are pure-blooded then what about the Dragonborn(should you choose to become one)? Won't that be a contradiction?
Also, how old could the Volkihars be?And are all the other breeds of vampires (look up "Immortal Blood" if you don't know what i speak of) pure-blooded too? Does that mean even they can become Vampire Lords? And why do we see no sign of the other breeds anywhere?And could these breeds have direct connections to Lamae?