I can't really verify magic in Stark other than what occurred in Venice prior to the collapse in TLJ, with images of Arcadia manifesting in reality (as witnessed by Fiona, Emma, Charlie and April herself). Also, Jacob and Cortez transforming into their original forms could have had a rippling magic affect in Stark. There should be no exceptions to the 'no magic' rule in Stark, hence why they were in human form up until the very moment they fought. It's also not a coincidence where in TLJ the white and blue Draic Kin were shown in their dragon forms, now in DF, the new white kin was in human form. I don't think the blue kin has not 'gone silent' like the white kin said, but is probably in human form, too. My bet is on the Blue Kin being Brian, meaning he's the Undreaming that possessed Brian. It would be prophetic that the 'Old God' is the one to destroy both worlds, wouldn't it?
Something strikes me as off about the blue kin. I think the duality also comes into play here. Cortez was 'good' and Jacob was 'evil', giving into the theme of balance. It would throw off the balance if the white and blue kin were both good, wouldn't it? Three good, one evil? Can't be. I put good and evil in quotes because I believe it's all relative. Cortez and the White represent the divide, and Jacob and the Blue can both be seen wanting to reunite the worlds. My only evidence to say that about the Blue is this: he seemed content with April for reuniting the Maerum and Alatien. Two separate species that didn't know of their common ancestry, like the humans of Stark and Arcadia.
I'm going back to what I said about Zoe and April being of Father and Mother. April's journey begins with the white kin, associating her with her role of Mother. Zoe's the only character other than the vagabond we've seen granted passage to Winter, then to the Storytime: the home of the Undreaming. Meaning she could be an affiliate of the Undreaming. If the Undreaming really is the Old God, then calling him 'Father' wouldn't be such a long shot. :P