Honestly I've been getting the feeling that Loki is going to surprise everyone and join Luffy. I took Loki's distain for the WG and the Celestial Dragons, plus the death of his animal friends, and the personal attack by Shamrock and his partner to set up a reason for Loki to at least be an antihero figure for a while. Considering where the story would have to go in order for Loki to go take those mentioned above out, he might just end up being a Strawhat for the majority of the rest of the story. Also, as an aside, I think Loki will be the one with the forest god abilities. Perhaps the previous user of the forest god devil fruit user was the one that made the Adam and Eve trees grow.
It would be an interesting twist if he had some complex or animosity towards his father or the world government due to shanks being the better of the two and being treated worse or having shanks' punishments taken out on him. This twist being a reason to give Luffy or Nami a document revealing more about the Nika fruits abilities or him further helping to train Luffy as a form of retaliation, however his partner in crime could be the one who sneaks off to let Loki free. Just a fun thought
Always thought it was an interesting "plot hole" that the sealing jutsu they used was "Phantom Dragons Nine Consuming Seals" when there were supposed to be 10 members, 10 fingers, ten rings but him leaving perfectly fit the number for the sealing technique
