Return a recursively created list from backend?

So, what I need to do is recursively process a series of linked records (think a tree) and return one result from each node visited as a thing-list.

What I am stumped on is how to pass and add to that list. Does it HAVE to be a field in the database for the backend workflow to update and return it? I could hang a temp field off of the user but that seems really ugly…

Okay i did it with a field on the user and it seems to work.

I guess the user “thing” is effectively my session data space?