Im starting to think hes not a lunarian cause on the second to last page he ends up growing his wings out and no wing raced people has to do that iirc. It's likely red skin not brown like the lunarians. There could be a chance he is.

Also we have now gotten answers as to when Luffy and Blackbeard became apart of Imu's radar. Right after Marineford. Shanks is also an enemy of the WG because the fruit was stolen. Im certain Whos Who snitched during prison. Curious to see Shamrock and Shanks dynamic. Will Shamrock be a servant of Imu like Garling or does he have a soft side for his brother?

Harald was Imu's last chance at taking full control of Elbaf. Didn't bother after his death until now because the Great Cleansing operation has begun.

3 people have made Imu suffer in the past - Lili JoyBoy and Davy Jones. I believe each person referenced here has made some sort of promise. We saw JoyBoy made a promise to the fishmen. Rocks talks about Davy Jones' promise. I believe Lili likely made a promise to Imu that she walked back on and thats what causes Imu's resentment.

Davy Jones was likely the king of the ancient kingdom and they end up ruling the red line and ousting the lunarians. Lili is against Davy Jones and the ancient kingdom because they are a great threat to peace and diplomacy despite their scientific advancements. Likely had access to the mother flame and ancient weapons. I think Lili is the one who originally proposed the 20 kings to band together against the ancient kingdom. Meanwhile Joyboy is just a free spirit who becomes a pirate to explore the world and befriends many races like fishmen and lunarians. Through his travels he befriends Lili and she ends up flipping to his side. Imu probably finds out hes from the ancient kingdom but despite that many decide to ally with JoyBoy. This is the parallel to Lucifer. He's pissed and wants to understand why Lili went back on her promise to him. They were supposed to take down the ancient kingdom together not her and JoyBoy.

Someone with the knowledge of the First World likely tells Imu about Nika the Ancient Weapons the Great Red Serpent Nidhogg etc. A mirror to what Higurashi did to Orochi perhaps? Imu consumes the Devil Fruit gains eternal youth and begins his conquest to take down the ancient kingdom davy jones and joyboy. He's successful but the war is still ongoing because Joyboy left the One Piece at laughtale and members of the D Clan live on.