I know Google+ controls the name that's shown in Hangouts, that's no problem. I'm in a large group Hangout, however, and recently some peoples' names have been showing up differently underneath their messages. One person's now shows his full name "John Doe (nickname)", whereas others only show first name, and still others show only first and last name (no nickname). How can this be set on a personal level (as in I can set how others see my name)? None of us made any changes in our settings that would affect this.
Google-hangouts – Change personal display name in Hangouts
google-hangouts
Best Answer
Short answer
Hangouts will display the "official" name in Google+ or in About Me if you are trying the new Google+. Users have several settings in order to choose how it will be displayed.
Details
"Old" Google+
To change how your own name is displayed in Hangouts,
New Google+
References
From Change the name on your Google Account - Google Accounts Help
Change the name on your Google Account
You can change the name on your Google Account by editing your Google+ profile. Editing your profile name in Google+ will change your name in all the Google products you use for this account. For example, you'd see your name change in Gmail if you send emails using your Google Account name and YouTube if you’ve linked your YouTube channel with your Google+ profile.
You can also edit other profile details such as your birthday or work experience, and control how you share that information by changing your Google+ profile settings.