I find this irresponsible of your parents. There should always be a spare. If you'd stop being so prudent and elaborate on the issue you're facing, I could assist in solving your lineage problem. There is clearly no solution only because you stopped looking.

[ Ciel doesn't understand how Kiyoharu could possibly be unable to produce an heir. ]

Back to the more pressing matter at hand.

You said: "Her family came to Japan with mine. According to her, one of her ancestors owed the Earl Phantomhive an incredible debt, and swore to always protect the Earl's family to repay him for his kindness. She doesn't know the precise details, but that may have been your Mey-Rin."

I find it hard to believe Rin would remain so loyal in accordance with continuing to repay an ancestors' debt without knowing the precise details of such a debt. She's withholding information from you if this is truly everything she was able to provide. Did she even specify which Earl Phantomhive? You're only assuming this Earl to refer to me because I've noted to you that Mey-Rin is the first of her line to join my household. Check your staff ledgers and interrogate her further.

Regarding S. How did you summon him? You also stated he 'saved' you. Elaborate. Omit no detail. I am especially interested to hear what you mean when you note he had an opportunity to break your contract and didn't take it.

Your Aunt. How did she die?