Smelt-Two Edge's Father

Given how vague and likely impossible that task was, I'm leaning towards the idea that Smelt was either a rival or otherwise did something to get on Greymung's bad side in order to get sent out on such a task. And given how Two-Edge mentioned that he and his father had carved out a 'secret world' for Winnowill during the Siege, he was likely a pretty danged talented troll. And given Two-Edge's devotion to him and how badly his death affected him, it can be safely said that he was a good father at least.

Something I never got though, was why after everything he had at that point, he decided to still carry out his mission for Greymung? Granted, that whole 'family' was little more then a social experiment for Winnowill to alleviate her boredom, and something was gonna give either way, but in THAT precise manner is still a bit baffling.