Sharing fields and their data between a user profile and a content type? I have a content type called "Profile". This is a standalone content type and may or may not be associated with an actual user on the site.

I thus need to find a way of sharing profile fields between the Drupal user and the new custom content type. In other words, if you edit the "home address" field on the Drupal user's profile page, that field (and its data) should show up on the Profile page associated with the user via EntityReference or Relation or whatever.

Is this at all possible? I know you can reuse fields across content types, but in my understanding, it doesn't share their data (Such that you can use field_something on content type A and again on content type B, but data from A will never show up on B and vice-versa).

Thanks!

(Addendum: My fallback is to just put all of the fields on the new Profile content type, keeping the actual default Drupal user profile relatively sparse. Moreover, I'm curious whether this is at all possible.)
I guess one option would be to use Rules, so that when one entity is saved, the field data is also saved int the field on the other entity.