How can a user create a reactive join or relationship between him/her and a list item on checked input


Is it possible to have a User check a checkbox on a list item from a collection and have that create a relationship between the list item and the user? I have a list from a collection called ‘Categories’ which I would like the user to ‘subscribe to’ and the data within the list, via a checkbox on each list item, when they do, i would like the user to view the list of all the categories they subscribed to. the data in the list item continually updates, This list is individual to the user.

What kind of code do i need to implement this? straight forward way of doing this?