By "subtitles", I mean the literary definition: a secondary title beneath a title, such as the "A New Hope" part of "Star Wars". If you're still confused, see Wikipedia's article, Software (titling).
I am transferring a document to HTML. In this, there is a title (I'm using an h1 for this), its subtitle, and body content (I'm using ps for these). I initially considered doing this as a small within the h1, separated by a br. However, knowing HTML5, I also considered aside. Bootstrap recommends I use a p class="lead", but I don't like the idea of it semantically being exactly as inportant as the rest of the article. What element best represents a subtitle in HTML5?