Okay, I'll take a semi-serious crack at this:
The sun powers the entire solar system. Any threat to it is automatically an X-threat. But who, besides maybe the TITANS or some other alien species, would try to destroy the sun? Well, maybe with a viable threat, you could hold the solar system hostage, dictating terms to every planet and habitat from Mercury to the Oort cloud. But that's just crazy. It's a comic book supervillain plot; real people don't think like that. And that's true, real people don't. But what about a memetic virus that thinks of itself as a supervillain?
During a solar storm, most of the surya population gathers in Ukko Jylina to wait it out. A very strange sound reverberates through the station, unlike anything they've ever heard before. They feel it in their sonar receptors, something loud but complex, like music. It's brief, the storm passes, and the pods swim back out and resume their normal carefree lives. But after a while they start trying to remember something: did they ever meet someone named Akaja Lacuna?
They say that there are no secrets among dolphins, and the same goes for Solarian Suryas. They ask each other the question. Does anyone know Akaja? Is she a surya? Maybe in one of the other pods? The name sounds vaguely familiar at first, but soon it becomes a common subject of conversation, then a hobby, then an obsession. Surely, Akaja must be in one of the pods. They all remember meeting her somewhere. And she was so charming and brilliant, a wonderful friend, unforgettable, a genius, the greatest Solarian to ever swim, our natural leader. Where did she go? Where did they take her?
The rest of the solar system notices nothing, until the first broadcast. A wide-spectrum radio message from Ukko Jylina declares that the Solarians have constructed an iron insertion bomb hidden deep inside the sun's surface. If their list of demands are not met, they will blow up the sun.
Demand #1 is that their leader, Akaja Lacuna, be freed from her imprisonment and returned to her solar home within 48 hours. It's a name that means nothing to anyone, except for a few insane Neosynergists and a couple of ex-Firewall proxies...
Better get a team together.