Hey Sunnyson, thanks for your reply!
To clarify, the local storage was just the version 1 idea, it will 100% be going to the database, but because my site can be used both anonymously AND when you are logged in, I need to store in the browser as well 
It seems like you still agree though, store the kittens against the user, and not store the users against the kittens, would you say that is correct?