1.  Facility keeping "mutants/metahumans" is destroyed in a breakout and a group of them flee by sea - or a flight of incoming transfers to a mutant/metahuman detention facility is brought down in the ocean before it can reach its destination.

They wash up on a deserted island.

Something akin to a superpowered Lord of the Flies.

2.  The population of the Earth has been decimated by a virus of some kind.  99.9998% of the population dead.  The remaining survivors all possess a mutated metahuman gene, which simultaneously provides the survivors with powers, and also was the genetic point of difference that allowed survivability.

All survivors have found themselves receiving a strange "calling" from at least one of two figures, and disturbing dreams of Angels battling Demons.  As the survivors are called to take part in the final ultimate call to arms in a battle of Good vs Evil.

3.  A group of superpowered metahumans have been "collected" by society's governments for a singular purpose.  To act as a preliminary terraforming group, in an extraterrestrial mission to find the Earth's successor as humanity have deemed the Earth unlivable.

They have been sent ahead to a small goldilocks world that with effort should be able to sustain human life.  Slow-moving "Arks" carrying the remaining human populus should start departing within 5 years, of mission success.

But it seems this world may already be occupied...

[hr]

4.  Ju-V..?

Juvenile Vigilante System/Program

In a world of great tension between superpowered people and regular humans, Ju-V is a last ditch effort by a desperate society to prevent the cataclysmic results of more superpowered "villains" from being created by a society which all too often sees an "Us and Them" divide between those with powers and those without.

Not a superpowered Academy/School, but a "rehabilition system" to instil morality and allow identified powered "Persons of Interest" (either from criminal act, wonton destruction, or a scenario primed for retaliation which would exacerbate the superhuman/human divide) the opportunity to learn how to control their powers and either not use them in the future, or display a newly gained sense of morality over when to use them.

Careful to avoid too close connotations to a school or Academy to avoid treading derivative ground.

It's instead a place designed to prevent the worst case scenarios of superpowered villainy from being unleashed on society as a whole.  With a focus on personal control and personal restraint.