Hi!
I think I understand. You want to use the correct display name of the users, not the “username”.
You will need to make a minor modification to the code for this to work.
Open up the wp-content/plugins/related-posts-pro/includes/related_content.class.php file.
You will need to change this string:
[code]$wpdb->users.user_nicename as author,[/code]
… to this string:
[code]$wpdb->users.display_name as author,[/code]
On the following lines: 89, 319, 546, 688, 721 and 746
Then go to the related posts pro options page and save the options without changing them. The author than should appear with the correct name.