At the moment, Papyrus Author does not support special characters, such as periods, in characters’ names.
If the surname Brown is unique in your project, you can use it in the ‘Additional Names and Unique Descriptions’ field to identify your character. You can add multiple names and additional names to your characters by separating them with a comma (eg. Eddie Brown, Brown)
Allowing periods for titles, such as Mrs. or Mr., would be a great improvement for the Character Database name field, and I will bring it up with the Development team. 
You can read more about The Character database in the wiki: My Characters