It’s the Harmony crest, drawn by lemongrove. Every part of the drawing has something to do with Harry/Hermione. It must be years old by now but I found it saved on my computer and I’ve always liked it so now it’s the sidebar!
There was a post (I think on harryhermione) that explained what everything meant but I haven’t been able to find it. Whoever can will have my eternal love and devotion!