RedheadEmber said: I don't think it was a father-son one, mainly because Windkin at that point was too old to even need a father
That is a fair point, but we don't honestly know. Cutter hasn't "needed" a father or mother for a long time, but his parents still come to him in spirit form at the end of Shards and provided comfort.
Windkin could have *wanted* it from Tyldak. We can't know for sure (at least not yet). I also can't say if I think one way or the other. There wasn't enough to tell from the flashback or Windkin's behavior, at this time. But, Windkin did have some of the same desires as Tyldak (wanting real wings and for Winnowill to give them to him), so Tyldak may have been able to provide sympathy and empathy.