(Source: hitorlesmis, via a-crack-in-the-tea-cup)
You can tell in the fifth gif that Sherlock is just so genuinely confused because this one man, John Watson, is somehow managing to surprise him. The second he thinks he has the army doctor figured out, or that he’s going to react to what he says like everyone else does, hatefully and telling him what a child he is, John laughs. And not at him like everyone else does behind his back, but with him. He genuinely thinks he’s funny and clever. John likes him. And it’s such a new feeling to Sherlock; you can tell in the sixth gif he’s just stunned but also so incredibly happy that I think he surprises himself and smiles/starts to laugh. He literally can’t even help himself because someone else finally understands his sense of humor and him in general. We already can infer that starting as a child Sherlock was made fun of and it continued his whole life; hell this could be the first time ever that someone has responded the way John does.
It might be a more understated scene in comparison to the laughter/jokes they share at other points like in Scandal, but it’s still so incredibly important because this sets up the base for those scenes; Sherlock knowing that John appreciates him just how he is. That he can be open and make those kind of jokes he does later. John Watson, the unassuming army doctor, lets Sherlock be himself and not only does he not judge him for it, but he enjoys it.
(Source: dimension-in-space, via cumbercollective-unite)