Hello,
So I'm curious to know if you guys have any theories or links regarding this. Please correct me if I'm wrong! (A lot was happening in the book and I may have missed bits!) In chapter 84 - "The One You Can Save", there is some dialogue between Sja-anat and Shallan:
We were made, then unmade, she agreed. But no, not an enemy! The figure turned humanlike again, though the eyes remained glowing white. It pressed its hands against the glass. Ask my son. Please.
Now is it possible that Sja-anat is Pattern's mother, similar to how the Stormfather is Syl's father? I personally don't see how that's possible, but Sja-anat saying "ask my son", sounds as if she is assuming that Shallan knows who Sja-anat could be relating to.
Also the fact that Sja-anat is known as the Taker of Secrets, and Pattern and Shallan's bond grows stronger when she admits certain deep truths regarding herself (such as killing her mother). Sja-anat can also change her appearance, thus looking like someone else. (Pattern is constantly shifting between different appearances).
The origin of the other spren associated to the Knights Radiant has never been fully clarified (as far as I know), could it be possible that the remaining nine spren types are associated to the nine Unmade, but before they became the Unmade? (This does clash with the idea that some of the spren are from Cultivation, and the fact that is a definite stretch, so I'm just throwing ideas out there!)
Best,
A Dopey Spren