So this is Gotham
and what have you done?
The Batman I once knew
never used a gun.
And so this is Gotham.
Joker's kissing Robin
instead of his usual
evil spree of robbin'.

CHORUS:
A very sad canon
unfamiliar to us.
Perhaps it was unwise
to leave it in your trust.

So this is Hogwarts
and what have you done?
Like Aragog's webbing,
a change you have spun
And so this is Hogwarts.
Ron has gone to the dark
the others now struggle
without friendship's spark.

CHORUS

So this is Kanto
and what have you done?
If you really need Legends,
limit it to one.
And so this is Kanto
and my eyes just bled.
Your Pokémon and you
should not be in bed.

CHORUS

So this is Sparta
and what have you done?
With all of the slash here,
the fight never begun.
And so this is Sparta.
Just see the effects
of history altered,
and all thanks to sex.

CHORUS

Story's over;
I don't want it.
Story's over now.

Bonus verses by KittyNoodles:

So this is Outland
And what have you done?
The whole Burning Legion
Is insanely dumb.
And is this Azeroth?!
The Lich King is high!
What's with the new island?
You've made Varian cry!

So this is Arda
And what have you done?
With so much canoodling
The Quest has not begun.
And so this is Arda—
But the Elves are in thongs.
There's shapechanging wenches
Wailing bad nineties songs.

[Feel free to sing with your own verses!]