Before teaching us about their usage Fiona gave us a quick description of who each card represented.

First there was Oberon. He was father to all the elder princes and princess of Amber. Oberon was the first King of Amber.
The next card was of Benedict. Foina said that Benedict had two brothers who no longer associated with Amber.
The next three were Eric, Corwin, and Deirdre. They were all direct siblings and half siblings to Benedict and his brothers. Strangely, all three of these people were presumed dead. I remembered Merlin speaking mourningly of Corwin, his father.
Then came Caine, Julian, and Gerard. I'd heard of Caine. Connie had told me about Luke's (Captain Loopy as he called him) many failed attempts to kill Caine. I also remembered Gerard. He was with Locke when last I saw him.
The next set of direct siblings was Fiona, Bleys, and Brand. I asked Fiona if there was a pattern or cause of each set of siblings containing three people. She seemed to think it was coincidence, but I made a note to look into this more closely. Fiona and Bleys had both struck me as being amazingly adept at Sorcery. Maybe this branch of the royal family was the most attuned to magic. Connie had mentioned that Brand might be his grandfather. Brand was presumed dead.
Next was a card of Lewella who had been with Locke earlier. I think she and Vialle were both from the underwater kingdom of Rebma. Lewella had no direct brothers or sisters.
Also siblingless was Flora. She was almost as beautiful in the card as in person. Was it a weakness that I long to know her better? I made a note than it would be gauche to Trump contact her merely to ask her to dinner.
Finally, there was Random. His sister, Mirelle's, card was ordered by Random, removed from the deck in her memory. Wouldn't it be unnerving to find the cache of Mirelle cards hidden away in an old box in the attic of Castle Amber?
The last card was not of a person, but Castle Amber itself.