User blog comment:MrPedroNorris/Biggest chraracter development possibility/@comment-5780397-20150301110347

Kalluto seems a good possibility, though I'd see his involvement in the story differently: wanting to bring Killua home, he tries to assassinate Gon, and I wouldn't be surprised if Illumi joined in, too. Being under the spotlight during such an emotionally intense trial could let us see him change, also considering his age.

One character who will have to develop for sure is Kurapika: as we have seen in recent chapters, if he survives the expedition and takes the eyes back, he'll have to find a new purpose to his life.

Personally I believe that it would be very interesting to know about Melody a little better, if she appears in the Dark Continent arc. As I've said in another post, I think she will try to be hired as a bodyguard by one of the princes who have sent the requests, having caught wind that Tserriednich is in possession of the Sonada of Darkness. Surely her hearing would be crucial to defend from ambushes and overhear secrets and plans. We might see her relationship with Kurapika change as they cooperate to get to the prince, and get to know her a little better.

That said, characterization is not really Togashi's strong point...