The Hyndluljóð is synopsized by Wikipedia thusly:

In the poem, the goddess Freyja meets the völva Hyndla and they ride together towards Valhalla. Freyja rides on her boar Hildisvíni and Hyndla on a wolf. Their mission is to find out the pedigree of Óttarr so that he can touch his inheritance, and the lay consists mostly of Hyndla reciting a number of names from Óttarr’s ancestry. The poem may be a twelfth-century work, though Bellows believed the material of which the poem was compounded must have been older.

But you can read the full thing for yourself here. It’s one of the shorter but more important of the Old Norse poems, if you ask me. 

And that’s because I believe that Óttarr is doubly disguised in it. First as the battle-boar Hildisvíni and secondly as Óttarr himself. Her champion is actually Óðr. He has been returned to her finally, but with significant gaps in his memory, which she hopes the Jötunness  Hyndla can repair. It’s so bad, in fact, that he actually believes himself to be the mortal hero Óttarr. Which, at least is an improvement on when he was first brought to Sessrúmnir and thought he was somehow Ohthere and Ótr simultaneously.

It’s been a long, frustrating road for them. As much as she had missed him in his absence (she shed tears of red gold for her husband) all the Tívar need him now, for he plays a pivotal role in the Final Battle, one unknown even to Óðinn, Frigga and the Nornir. If they knew, it would be possible for their enemy to learn of it, and make the appropriate corrections.

Which makes Óðr’s partial amnesia bad. 

At least it only seems that bad. In truth, it is much worse. You see, he’s only pretending to believe he’s Óttarr – he really thinks he’s Amlóði.