All credit to the artist Itanatsu-chan. I found their deviant art, but haven't found this particular piece of art yet (I simply could have over looked it whilst scrolling their extensive gallery). Here's a link to their deviant art to show them some love.
Sebastian in every ship expecting every scenario to turn sexual but when his lover wraps their arms around him and pulls him close and just lightly kisses him and doesn't do anything else he starts getting squirmy and flustered and confused