I wonder what the purpose of the paradise is, his end goal with that isn't clear to me.

Same, I'm confused as of now. I'm thinking he's probably looking for the one person who is 100% pure soul. As even though your a good person, experiencing something new , isolation, or trauma can drive even the happiest person insane. He's probably looking for that one soul that can overcome/never be corrupted, in order to give him hope for the future.