She's no longer a child. The Archive must be passed from mother to daughter.
WHO is the father (husband?) going to be? Obviously her bodyguard, the Hell Hound is too old and (ICK!) their relationship would preclude such interaction. The same could be said of Harry.
One of the Alphas or one of the Carpenter sons would fit this role nicely (particularly if either pick up one of the swords).
Barring either, Butcher could create a new character who mates and betrays The Archive which complicates Harry's life in horrible ways. Perhaps an Outsider who masquerades as ... who-knows-what. Perhaps a member of the White Court, but The Archive would probably see right through one of their nation.
Just thought I'd throw the subject out for discussion.