How to create a user hierarchy

Hello,

I want to represent a hierarchy of the registered users on my drupal 7.

To stay simple, I want each user to have a unique hierarchical direct superior and I want to be able to create pages (views maybe ?) to see the whole hierarchy.

I also need basic permission management to edit the hierarchy (users should not be allowed to edit their own superiors, and it would be really great if they were allowed to edit anything beneath them in the hierarchy)

The goal is not to manage Drupal's right this way, the goal is only to display the tree and maybe send messages to a limited portion of it.

Is there any module or any simple way to do it ?

Thank you for your answers.