I made a Theory long ago, saying that SHs have Major Figures who Mirror them in this Story,
Usopp, Jinbe & Chopper were "Isolated" Trio of SHs, while Zoro, Sanji & Franky were "Lost" Trio, and Nami, Robin, Brook were "Homeless" Trio,
Isolated Trio are mirrored by Three Isolated "Great Figures", and They are like to those SHs what Mihawk is to Zoro,
Meaning We should have Someone who can heal his Patients from anything, and Someone who is from Fish-Men Island but is Loved by Humans, and Someone who can be described as Brave Warrior of The Sea,
You think it's coincidence that Shirahoshi was Introduced in Isolation? Same for Imu? Same for Loki?
How do these guys Stories mirror SHs? It's by following pattern of "Same Coin but Different Face", meaning They share similar Storylines but for Opposite Reasons,
For example, Jinbe was met in Fish-Men Island living in Isolation because He was seen as a "Criminal",
What about Shirahoshi? She was living in Isolation because She was being Targeted by a Criminal (Vander Decken XI),
Now for other Two, Usopp was seen as a "Liar", while Chopper was seen as a "Monster",
This is why I theorized long ago that Loki is Imprisoned because He is Targeted by a Liar, while Imu lives in Isolation because He is targeted by a Monster, (Actually this fits with what Corazon said as He told Law that CDs tell their Children to behave or D. will come & eat you, also known as God's Natural Enemy).
Imu refusing to go to Elbaph when Harald Lost shows that He does acknowledge that there is Someone who can beat him, but after confirming that Harald was Killed by Nidhogg, He confirmed that it wasn't who He thought it cd be, and decided to pay Elbaph a Visit,
(These Chapters also confirm that Loki didn't interact with Holy Knights or Gorosei or Imu before, and They didn't know about his DF, confirming that Loki was instead targeted by Someone else, and that's why Shanks captured & imprisoned him),
Imu leaving his Castle + Loki freed only exists to make these Two Figures reveal themselves (The Liar & The Monster).
It's safe to assume that who is targeting Loki is none other than Man With Burn Scar, while who threatens Imu is a D.
(Also teased by Vegapunk's Message saying that One among D. is ......, and also by Xebec asking if Imu fears Joy Boy or Davy Jones more, and you can also see his Reaction when Lily was revealed as D.)
I personally don't care about Imu vs Luffy or Loki or Zoro or anyone in Elbaph,
I'm just waiting for Lore Piece & Reveal of Endgame Version of Noland (The Liar) and Kalgara (Demon of Shandora).