Lestrade was reeling. Sherlock and John were outside meeting the reporters and he was left upstairs with his heart breaking. How on earth did this happen?!
It all started so innocently.
He'd been so happy when Sherlock walked out of the shadows and revealed himself to be, against all odds, still alive. Lestrade hugged the younger man before he could even think of potential repercussions.
The weight that had been on his shoulders for over two years evaporated as he held Sherlock. He'd felt the other man tense before he seemed to relax into the embrace. Amazingly, he hadn't wasted away in the years he'd been gone. Sherlock somehow seemed more solid, more muscular than the rail-thin man Lestrade had buried. The DI had managed to pull himself together and release the younger man before the moment became too uncomfortable. They'd exchanged brief, meaningless words before the resurrected detective had sauntered off, confident that his relationship with the Yard had been restored.
Greg knew he'd done the right thing by not telling the other man just how devastating his death had been. How Lestrade had wept over his headstone countless nights, a cheap bottle of whiskey clutched in his grip, mourning the loss of great man, a man he came to realize far too late that he loved with all his heart.
Instead, he'd said nothing. He'd kept his buried-but-not-gone feelings to himself. He played his usual role of world-weary Detective Inspector and paved the way at the Yard for Sherlock to resume his role as a consultant. Thank God, Moriarty had been proven a fraud and Sherlock's name had been cleared shortly after his 'death'.
When John had called to say Sherlock was having people over to 221B Baker Street as a sort of homecoming for the detective/mini-engagement party for the doctor and his new fiancée, Lestrade had agreed to go. Any chance to see Sherlock again, to remind himself he was alive and well and not rotting in the ground was a welcome one.
Thus Lestrade found himself greeting Molly and her Sherlock doppelgänger of a fiancé, making small talk with Mrs. Hudson and Mary. Lestrade was helping himself to some champagne when he heard Mary telling the story of how Sherlock had revealed his continued existence to John. He chuckled at the image of John tackling Sherlock in a fancy restaurant and then again when Mary mentioned the doctor scrabbling over a table to attack the consulting detective resulting in the three of them being tossed from two places in a row.
Mary is giggling, as she regales Molly and Mrs. Hudson on the sofa. "… And then, just when I think John is starting to come around, to maybe calm down enough to truly hear what Sherlock is trying in his infuriating way to say. The bloody man says something about John about missing 'the thrill of the chase, the blood pumping through your veins, just the two of us against the rest of the world.' and John headbutted him in response! I swear I've never been kicked out of three different places in one night!" The ladies laugh, and Molly's fiancé, whatshisface, smiles awkwardly and Lestrade can't hear anything else over the sudden ringing in his ears.
'Just the two of us against the rest of the world'
Lestrade hears that phrase in Sherlock's inimitable baritone repeat over and over in his mind.
'Just the two of us against the rest of the world'
He abandons his champagne flute and staggers over to an armchair and lets his body drop onto it. Sherlock's chair, 'of course, bloody typical, Lestrade!'. Even his subconscious is drawn to the sodding man.
'Just the two of us against the rest of the world'
Lestrade shakes his head trying to rattle the voice from his head. Thankfully everyone is engrossed in Mary's story and no one has noticed the devastated man across the room. 'I guess there's your proof, Lestrade.' He thought bitterly. 'Sherlock never considered you anything more than "the rest of the world", a necessary evil to grant him access to cases.' He brought up his hands to massage his suddenly pounding head.
'Just the two of us against the rest of the world.'
Sherlock's voice in his head seemed to resonate, banging around the inside his skull. "Shut up." Lestrade hissed.
Molly looked over at him from the sofa. "Greg? Are you alright? You look a bit pale."
The attention of the room shifts to him and he feels the need to get out of there immediately. "Ah no, seems I've a migraine coming on. I'm going to head back to my flat, have a bit of a lie down." Lestrade stands and goes to gather his coat.
The women all coo over him, wanting to help, and he grimaces, waving a dismissive hand. "I'll be alright. I get them every so often," he lies. "I'll see you all later. Congratulations again, Mary."
He bolts down the stairs and out the door. Once outside, the throng of reporters barely spare him a glance. John looks back over his shoulder at him but Lestrade just waves and walks away at a brisk pace, a single tear sliding down his cheek.