Stop me if you've heard this one... John/Sherlock

Sherlock Holmes was sat in the leather armchair, managing, as usual, to appear at once both rigid and boneless, lounging comfortably but deep in thought, fingers steepled in front of his face. On his lap, inexplicably, was a small black kitten.

and One Time He Did Something About It. John/Sherlock.

John/Sherlock. Lestrade notices things that everyone else doesn't.