Retrieve only specific columns from find() method

Intuitively, I would think that if you would like to retrieve only specific values from a model that is retrieved in Eloquent using the find method, it would look something like this:

        return Auth::user()->some_model()->find($id)->get(['col_a', 'col_b']);

What it seems to do, however, is return ALL models in the database with 'col_a', 'col_b' values for each of the models (associated with that user in particular).

How would one only get the model returned by the find($) and then grab those two columns? Worth noting this is in Laravel 5.4