If I were writing an outline for Osgood's return:
Since she idolizes the Doctor so much what would work, especially with this Doctor who questions whether he is a "good man" or not would be that he does something morally ambiguous and it is Osgood who has to set him straight. In the end her actions prove to be the right ones and the Doctor tells her that she shouldn't emulate him since she is the better person. Osgood is hit with the reality of that and strives to be her own woman. As her reward, the Doctor gives her a trip in the Tardis.
Maybe a bit heavy-handed as a morality tale, but I think it would also serve as a way to nullify people's main complaint about Osgood; her uber-fan-ness.
Since she idolizes the Doctor so much what would work, especially with this Doctor who questions whether he is a "good man" or not would be that he does something morally ambiguous and it is Osgood who has to set him straight. In the end her actions prove to be the right ones and the Doctor tells her that she shouldn't emulate him since she is the better person. Osgood is hit with the reality of that and strives to be her own woman. As her reward, the Doctor gives her a trip in the Tardis.
Maybe a bit heavy-handed as a morality tale, but I think it would also serve as a way to nullify people's main complaint about Osgood; her uber-fan-ness.