The premise of the meme is simple. Two characters, lovers, have been separated for a time. How long is up to you, as is the reason for the separation. Was it unwilling - an imprisonment, a required journey - or because of a choice one of the characters made? The reason may, of course, color the reunion, and somebody may be pretty miffed, with good reason. Still, the theme is the same: intimacy after being apart.
This meme is mostly geared towards being a smut meme, but nobody will judge you for just doing so heavy fluff.