Sion really loves Dino, and is completely persuaded that he is a better person than he is. :'D I think I told you once that he sees him as some sort of little brother who turns out to be better than his older sibling. So it's safe to say that he is very proud and protective of Dino, even if a little envious as well (especially when it comes to Mally, but he is getting much better at that o/). Most of all, Sion thinks Dino is a very good person, capable of reaching people's hearts and communicating with them. Emotions and ethic values rank very high for Sion, so he pretty much sees Dino as Onyx's heart and soul. That's one of the main reasons why he thought he should represent the team. Sion's favorite hobby is to recognize talent and put it to good use, and Dino is an awesome Onyx as far as he is concerned. :D It's funny that Dino sees him as a leader because Sion sees himself as Onyx's caretaker (regardless of a leadership role), waiting for someone who is morally superior to take his place, much like he sees himself as a carataker/servant king in canon, waiting for Ryner to decide to be king instead (spoilers: he is still waiting. XD )

Dino and Onyx?