What has gone before (behind the scenes) ...William Stryker owns Aegis Corp., a company that specializes in dealing with mutant threats -- corporate espionage, terrorism, mutant stalkers, etc. Akin to Blackwater, Aegis employs a paramilitary force of ex-special forces, but also hires on former intelligence agents and has some boffin divisions for developing anti-mutant weapons and restraint technology. Under contract from the US government, Aegis designed, built, and operates Stronghold, the prison that contains Magneto (along with several other mutants). The wreckage of the device (Magneto's 'mutantizer') found on Liberty Island has also secretly been turned over to Aegis.
Stryker knows the true nature of the School and has had it under surveillance for some time. Aware that Xavier is a powerful telepath, Stryker has used satellites and remote drones and has a tape showing Kelly arriving there and then collapsing into Logan's arms. From the outside angle at which the video was made, it looks as if Logan might have killed Kelly with his claws. Not wanting to attract attention to his goals or the extent of his network, Stryker has not yet made the tape public or even revealed to the government what he knows.
Using his mutant son in an attempt to recruit Henry Peter Guyrich, a former colleague from military intelligence, Stryker discovered that Guyrich is highly resistant to telepathic powers. Aware that Guyrich wants revenge for the murder of his own son, Kelly's aide, mauled to death by a clawed mutant, Stryker has told him about the X-Men and shown him the tape. Guyrich remains not entirely certain Wolverine was responsible, but has agreed to spy on the School. With assistance from Stryker, Guyrich has been established in the cover identity of Harry Peters, a harmless and friendly new resident of Greymalkin Lane.
Using the mind-control serum developed from the brain fluid of his mutant son, Stryker has been questioning Magneto. He has learned about the names and abilities of the Brotherhood and the names, abilities, and sometimes locations of other mutants Magneto has discovered. Protocols have been instituted to prevent shapeshifters such as Mystique from gaining access to the prison. Stryker also knows that Kelly is dead. Most recently, Stryker has learned the function of Magneto's device and has set his own techno boffins to work on creating a device with the reverse effect -- turning mutants into humans.
While he waits for progress on that front, however, Stryker continues his covert anti-mutant crusade by other means. He has captured the demonic-looking mutant Nightcrawler and is preparing to turn him into an assassin.
As the story begins ...With the apparent destruction of the Brotherhood, the X-Men have some down time to recover from the last crisis and ready themselves for the next one, which will be arriving all too soon for their comfort.
OOC: While people join up and various roles are filled, go ahead and pose your characters doing whatever they do when the fate of the world isn't hanging in the balance.

There's the Danger Room, mutants to be rescued, or just gabbing in the kitchen or out by the pool. Friendly neighbor 'Harry Peters' can usually be found hanging around Salem Center as well, and he's always up for a chat.
Mini (and not so mini) plot suggestions are always welcome as well, feel free to post them here.