Here's how Jason and CK (Superboy Prime) can plausibly meet:
Someone is threatening the cape community. Maybe a virus has been developed, maybe civilian identities are being leaked one by one, maybe it's aliens again. Regardless of the specifics, the most important thing here is is that it can in no way be Red Hood, not his MO, no connection to him whatsoever, so, obviously, the bats (Bruce, Dick, Tim and Damian in particular) go "It's gotta be Red Hood!" The other heroes believe them unquestioningly and join their hunt on Red Hood. Since this is not Jason's first rodeo, he evades them until the actual culprit is found. Maybe one of the capes kills him accidentally, but because Jason pops back up, perfectly intact, the bats think he faked his death and get pissed at him for putting Bruce through this again.
Jason does not get a single apology.
Fed up with this shit, Jason has one of his soliloquies where he tentatively feels he's trapped in a narrative due to the sheer absurdity he has to deal with without actually coming to the conclusion that he's a fictional character. Instead, he finally decides to figure out what it is that keeps bringing him back to life so that he can stop it.
And here's where the All Blades come in! Jason emulates his trial where he was in the stream of past, present and future by submerging himself under water in his bathtub in the hopes of catching a glimpse of what actually happened. The reason why he hasn't done this before is that it's extremely dangerous. His soul might shatter, but at this point, he's willing to take the risk because he's losing bits of himself slowly as is in this limbo.
He gets a vision of Superboy Prime punching reality, which is an extremely confusing picture without the context readers have, so while Jason is trying to make sense of what he's looking at, SP in his vision suddenly freezes and looks RIGHT BACK AT JASON. His facial expression shifts from that of a cornered animal to a confused one, like he's just woken up, but it's clear he sees Jason too. This startles Jason so much, he gets kicked out of the vision and comes back up for air. Overwhelmed, he gets out of the bathtub, gets dressed and goes to the kitchen to get a cup of tea. Or a bottle of whiskey. He hasn't quite made up his mind yet.
And who's floating outside the huge ass window of Jason's living room but Superboy Prime himself! How long has he been there? Who's to know? Jason can't hear him through the glass, but he can read his lips: "I just came to talk." Ok, sure, at this point, why not? He just saw this guy alter reality with his fist, but whatever. On the other hand, SP could just break through reinforced glass, and Jason doesn't want to have to install new huge ass windows on whatever floor he's on, so he lets him in.
SP is freaked out that Jason is poking into his resurrection. He's never done this before, why now? Dear Reader, are we addressing the narrative implications in this one?
Unphased by SP's reluctance to explain what he saw in the vision, Jason decides "If you're the one who brought me back, you probably have what it takes to kill me off for good. Let's try!" So SP, horrified, has no choice but to explain that they're in a comic book universe as gently as he can muster. He gets C+ for effort, but again Jason doesn't even blink. "Was I just not a lucrative character, or something?"
SP has gotten used to his fourth wall breaks being dismissed as him being crazy, but now someone is listening to him and actually considering what he has to say, so he lays it all out:
"There was a poll on killing or saving you. It was rigged."
"So, the writers just don't like me?"
"I take it, most don't. Why would I wish for death if I was loved?"
"Must be painful for them to read about me all things considered."
"It is. But no matter how many times writers try to make you unlikeable, you still come out sympathetic. Heroic. That's what keeps us reading your issues."
"Is that why Bruce is so different? There was a reason I loved him. Before."
"You won't kill me, will you."
"I've just had my redemption arc. I don't want to be the villain again."
"I'd say it would stay just between you and me, but apparently we always have an audience."
"Nothing stays a secret in a story. Chekhov’s gun and all."
"Pfft, I've got plenty of secrets. No one has connected the dots that I'm functionally immortal - it's not like I go out of my way to hide the scar on my throat. They don't care."
"It's because you're intentionally isolated from other heroes. And the repercussions to my character aside, I don't want to kill you."
"Who are you to decide whether I get to stay dead or not?"
"I'm a fan, Jason. I'm sorry."
