I can't express how much I love this picture *w*
The lighting. Warm and soft, comfortable and still accentuating the two characters (especially Sherlock's dark curls *w*)
The poses of the two. Sherlock, holding John with this little-something-making-him-so-sexy-and-still-it's-a-casual-hold; his slightly possessive left arm around the shoulders of John, keeping him close, "capturing " him and however being so sweet, like for a hug; his right hand unbuttoning John's shirt, it seems to be a casual gesture but still we know there is more behind this >:3
John holding back Sherlock's wrist, but softly, like he's a little bit afraid of what will happen but doesn't stop Sherlock like he could; he let Sherlock's fingers keep unbuttoning his shirt and doesn't try to stop more.
The expressions. Oh Gosh the expressions. I don't know which one I love more, so let's say I love both, in a whole, the little knowing smirk on Sherlock's face but his tenderness and possessiveness present, as to respond at the confused look on John's face, like to say "I'm the same Sherlock you know, trust me"...
Really, I could find a bazillon other things I love, but I'm maybe finding too much details
;; great fanart, you deserve