When I say "shuake are soulmates" I'm not talking about Yaldobaoth choosing to pit them against each other. What I actually mean is that even before Joker and Akechi met, their souls (personas) already chose each other.
Robin Hood and Loki predate any of the phantom thieves' personas. What is Robin Hood? An honorable thief. Basically a counterpart to Arsene's gentleman thief.
Even more interesting is Loki. The rest of the Thieves only get their persona upgraded to a 'mythological trickster' upon their second awakening. From a purely gameplay perspective, you spend time with Joker's friends in order to give them stronger personas (grind and reward).
But Loki is known as a trickster god in Norse mythos. He is already a mythological trickster. From the beginning, Akechi was already what Joker needed him to be.
And then there's Arsene, who is so blatant that he's the reason I clocked shuake's soulmatism from the moment Joker awoke him (literally in kamoshida's palace I figured Joker would meet a detective rival in the story). Basic Arsene Lupin lore is that the character was written by author Maurice Leblanc as the 'French response' to Sherlock Holmes (for copyright reasons it's herlock sholmes).
Arsene exists because of Sherlock. So of course Joker is so obsessed with Akechi in-canon. That's literally what his soul is built for.
There's another layer to this.
The name "Goro Akechi" is inspired by the Japanese detective character "Kogoro Akechi" written by Japanese author Edogawa Ranpo (this is also the reason I clocked akechi as the rival the moment he introduced himself, I did my time in the BSD fandom). Kogoro Akechi is a detective character heavily inspired from Sherlock Holmes.
Edit: Forgot to mention that Kogoro Akechi's most infamous rival in the novels is named Kaijin or 'fiend/strange person' (originally Kaito Niju Menso, or Phantom Thief with Twenty Faces). Ranpo based that character on Arsene Lupin.
So Joker's soul is a thief character written to rival Sherlock Holmes, while Akechi's name comes from a detective character written to emulate Sherlock Holmes. Alone, they are incomplete. They've been searching for each other from the very beginning.
Joker and Akechi are fully soulmates, regardless of evil gods using them as pawns. No one else matches to the degree that they do, no one is as entwined as they are. Nothing had to trigger or evolve for this to happen either. They were just made for each other.













