Suzanne

For Genesis child themes that output HTML5 only.
This plugin adds an entry field just below the title field on all post, 
page and custom post type edit screens. It allows you to specify a 
subtitle for the content and then outputs the result in an H2 tag just 
under the entry-title where you’d expect to find it.
This plugin is for use with Genesis HTML5 child themes only because it 
uses the hook, genesis_entry_header to position the output after the 
title but before the post-info.

Genesis Subtitles

For Genesis child themes that output HTML5 only.

Mostafa Shahiri

The Small Heading For Post Title is a simple plugin for displaying subtitles before or after post title. It is a useful plugin for the websites 
such as news websites that display some small headlines or captions before or after the main title. This plugin adds a meta box to your page/post forms 
in admin panel and you can determine a custom text as the subtitle and position of the text, then it will be shown before or after the post title based 
on your choice.
Also, in settings page of this plugin, you can add some CSS codes for styling the subtitles and you can determine and control that subtitles 
are shown in which sections of WordPress (See screenshot images).

Small Heading For Post Title

The Small Heading For Post Title is a simple plugin for displaying small headings (subtitles) before or after post title.

Genesis Subtitles vs Small Heading For Post Title