I was trying to sort out the odds of this switching being not 'displacement' (I take your spot, you take mine) but 'round robin' (that's actually more Lovecraftian, once we get into the dreamlands stuff, where everything has a counterpoint but just because you come or go doesn't mean you can come or go -back-, even ever.... the whole frame can shift, all of your counterparts and the reference frame shifting with each shift so there is -no- back to go to, and just because Yellow King came here doesn't prove where Psisquid went or how to bring him back).
Then I realized that if round robin was going on, Nihlist would not have needed to be told that he was in an alternate reality. It would have been the -second- flip for him, and he would only have needed to understand our flavor of reality, not anything about the actual change. So Round robin is out.
And our Psisquid probably is in Yellow King's reality, still. Alive or dead, injured or not - because Nihlist also lied about what happens to one of them happening to all. That was never true - because he doesn't know if it's true or not - that was said to work our fears and intentions and to protect us from him - that Psysquid had more fear of us than he dared show. The Psysquids are different, and the switch through our reality is their only intersection with each other (thank the Elder Gods.... Round Robin is -way worse-). That loss of a tentacle is a form of proof of that.
Then I wanted to question Yellow King about what would be done to our Psisquid in Yellow King's Overlord's hands.... then I realized that no matter what, more time in this situation doesn't help Psisquid. It's probably either 'already to late', or he's in some ongoing unpleasant experience. If it's too late, maybe Yellow King will fail when he tries to return, maybe King's the new Squid.
But I want to try, so we send him back fast.
But we don't have to send him back so fast that he's still broken. We are control. We are a fixer. And we have Standards. So we Make It Quick.
We need eye contact with Yellow King. We need physical contact. We -take- his mind, his attention, we become either his sense of self or we surround his sense of self so closely that to him it is a shared thing. We touch him in that way with our strength, we -take- his will.
And then tell him, "You are what you have always been. Every you that is, is. You exist -within- -my- -power- -now-. This is the core of what -I- am, unlike the Overlord that is yours. And I can change you. Again. Here, I created you. Here, I make you again. Choose what you want to be. Choose what you want to forget, what you want to remember. I will make it true as you reach for what you choose."
And listen closely. If he suddenly feels - or if we suddenly feel, the 'feel' of "Our Psisquid"... that probably means that ours is already dead. Pull that feeling in, make it one with this one, and make them together whole, together one, with the feel of our Psisquid dominant and truest, the other also there and welcome.
If we don't feel Our Psisquid as we do this, simply heal him in the directions he goes, in the directions he feels strongest in.
Then release him, and as we draw the power of our mind back from him and leave him a single and unbound soul again, keep eye contact as we command him - if you return to your world and realize that Our Psisquid died there before you came back to there - return to Us. You have tasted Our strength, shared it - you are also Ours now. Return to me, and take the place of what We have lost.
Then command him to return 'home', as whole and strong as our might has been able to recreate him to be.
Remain ready to repair Our Psisquid when he returns to us. That may be needed.