*Ahem* Now is when I quote the Ansem reports (In a sense)
First of all, it isn't 'paradise' it's 'world'
There's the world of darkness,
The world of light,
And then the world inbetween. (I might be off, but this is mentioned in Ansem Report 12 of KH, where he mentions the places of darkness, light, and in-between)
I'd doubt he's searching for just darkness, if you find all three, he could destory light and in-between, and take over dark.