I feel like this Arc/Saga is Hyping the Alternative Versions of Kaidou's Top 5,
Basically Heroes/Law Enforcers Edition instead of Pirates/Criminals Edition,
It's like Oda wanna show us the Other Side of this World/Story,
He starts with Introducing Shamrock as WG Version of Shanks,
An Introduction that further Confirmed Garling as WG Version of Roger,
Then this Elbaph Arc Introduces us to an Oden-Like Flashback Character (Harald) but He is on WG Side,
And during this Flashback, We can clearly see that Rocks & Hachinosu are like Pirates Version of Marine HQ,
(While Roger Pirates & Red-Hair Pirates are Mirrored by Two Generations of Holy Knights),
This means that WG-Side Version of Xebec/WB are simply Sengoku/Garp,
So if We replace Kaidou's Top Five with Shamrock, Harald, Garling, Garp & Sengoku, then their Main Enemy (Their Kaidou) is an Apprentice of Garp/Sengoku + Enemy of Garling/Shamrock, and that's obviously none other than Monkey D. Dragon!
What's Crazy is that this means Harald's Killer or at least who Plotted his Death is None other than Dragon, just like Kaidou is Oden's Killer,
And another Major Hint is that Oden's Successor ended up acquiring same Powers as Kaidou, this means that if Loki has similar Powers to Dragon, then it makes this Theory super Convincing, and after seeing that Loki Thunder Bolt, you can't tell me it didn't remind you of Dragon's Introduction.
This is just Food for Thought, but i believe that Dragon is a Prime Suspect in Harald's Death,
Elbaph DF might simply be Dragon's, and it makes sense that WG's Enemy No. 1 has it now.