I don't really know what should be happening, because Higba never turned up anywhere near the Nameless Isles for me. I rescued him, and left him outside of Driftwood where he decided he wanted to hide in his fish barrel until the whole voidwoken thing blows over (paraphrasing, but he really did jump back in his barrel on the far side of the bridge and say something like that when I asked why).
I'm playing as the Red Prince, so I don't know what affect that has on it; I don't see why it would have any. Delorus joined me for a bit on the island, but that was it for people from the past showing up I think... then again, I did kill pretty much every magister between the Joy and the Isles, so Delorus was one of only 4 reds that could have shown up.