User blog comment:BrooklynGuido42/Where do non nords go after death?/@comment-2219562-20120710021416/@comment-3523404-20120714035632

There are no reliable sources that state Alduin is the son of Akatosh in a divine sense. Technically, all creatures are the offspring of the Aedra. But that's neither here nor there.

To answer OTP's question, where do the souls of those who are soul trapped go? Soul Cairn, we know from Dawnguard. But, what happens to those souls after the soul gem is broken or used. Probably the same thing that happens when a Dragon Soul is absorbed and spent to unlock a Dragon shout. It's energy is used up; it ceases to exist.