Adam didn't know all the secrets of the higher nobles and how the Twelve Branches were organized, especially such dark and bloody details as about the firstborn.
However, because of the general atmosphere and Franz's words, he roughly understood how rare yet important someone like Baren was.
Every great family had a firstborn, it was inevitable as sooner or later a Phantom would appear in great families, especially considering how many people were in the same family, carrying a powerful bloodline.
But, the same could not be said for True Firstborns. They were a rarity, in some ways much more infrequent than the Natural Phantoms, even though they were such in their origin.
Adam might not be as knowledgeable about Baren's status, but everyone here was well aware of it.
