Maybe I'm jumping out of context here, but would  `_.result(this, 'model').prototype.parse` cover the factory case? This still leaves the context problem though...

I used to use a simple relation following mixin that hooked itself to the model in the parse function, so I relied on the model context in there. I don't do that any more, because of the complexity it introduced, but I can imagine other people relying on the model context too.