I initially thought of Sorcerer but I think Warlock is actually the more flexible fit thanks to the invocations. For example, Devil's Sight and Whispers of the Grave would be good fits for a scion of Hades or Persephone, Beast Speech a good fit for a scion of Pan, Master of Myriad Forms for a scion of Zeus, and Thirsting Blade for a scion of Ares or Athene.
Step 1: Create Draconic Sorcerer.As for the Sorcerer option...this just falls under the "family ancestry" we have been given in the Draconic Sorcerer. We don't acutally need Elemental Ancestry, Genie Ancestry, Divine Ancestry all as separate sub-classes...Just take the dragon sorcerer and swap out other powers of similar potency at the appropriate levels that, flavorwise, fit whatever your ancestry of choice is. We have the "Innate Magic/Powers from Ancestry" sorcerer already.
Step 2: Swap appropriate warlock invocations for Draconic bloodline powers.
Step 3: Rename sorcerer to "Child of [Whoever]."
Step 4: Profit.
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