I don’t really have any evidence for this assumption, at least not hard evidence. However, in the scene where he accidentally walks in on Shallan in a nightgown, I noticed something odd he said.
He said, “...my name is Adolin Kholin, I was born under the sign of the nine...” Knowing Brandon, I wouldn’t dismiss this as coincidence out of hand. We know Braize, Odium’s Invested planet, is related to the number nine. Since Preservation’s number was 16, Honor seems to be 10, while Odium is 9. Nine shadows of his Champion, Nine Unmade, etc. We have WoB on that, can’t find it.
Anyway, what is “the sign of nine”? Why does it happen that a main character, who has had nothing special happen to him as an individual thus far (at least in comparison) suddenly mention this supposedly unimportant fact in passing?
Coincidence? Not likely.