Disclaimer: Nothing you recognize is mine.
Some ideas might have been nicked from different fics.
Severus's POV
Dark. After the blazing blue sky over grassy field the sudden darkness felt like a soft handkerchief over his tired eyes. Ever so slowly his eyesight adjusted to the semi-darkness of an almost empty room with the only shuttered window. May be due to the semi-darkness but most likely the brown wooden walls and the floor of the same material illuminated but by the soft light gently passing through the window the room felt almost like the comfortable little candlelit cabinet in his favorite Italian restaurant in the Muggle London.
Just as slowly his eyes drifted to the black dragon-hide battle robes then the impassionate face of his once most-hated student, later the only Ally on the side of Light. "Ally". He almost laughed at the word unbiddenly coming to the forefront if his mind. Some secrets were meant to die with their Keepers.
Bemused, he took another minute to access the surroundings of what looked like one of the Order safe houses.
ten minutes earlier
Standing by the Dark Lord's side he was dueling with Kingsley Shacklebolt, his Death Eater mask long since torn from his face by a stray curse, his battle robes flaring behind him like the wings of a giant bat his students so compared him with, when out of the corner of his eye he saw a column of light envelope his one time Master. Transfixed, he couldn't tear his eyes from the ghostly figures floating, as if in slow motion, in and out of the light globe, recognizing many of Voldemort's all times victims circling the wizard, going round and round him in ever tightening circle, shining so brightly he could hardly bear the light… And then in a flash they were gone, and with them the now mortal body of the most feared wizard of the century.
The time sped to its normal pace and he became aware of a searing pain in his left forearm and of a Blasting Curse connecting to his side, tearing through the dragon hide, slicing the flash of his right underarm with its backlash.
Staggering on his feet, he rose his wand in mock-salute, intending to drop it in surrender when another figure Apparated between him and the Auror, gripped him vice-like by his wand-arm and Apparated them away. The last thing he saw was the Auror "24 hours later" sign made by this new assailant to the Order member.
Disoriented, he felt thin snake-like ropes securely tie him to a high-backed chair in the sudden darkness of this room, wherever it was..
back to the present
"Give me one reason, Snape." Rasped the voice of the other wizard.
His gaze snapped up and could no more leave the parchment-white face and flaring green eyes boring into his, trying to see the very bottom of his soul. He absentmindedly noticed the streak of blood from the freshly-opened lightning-bolt scar and a muck-covered eleven-inch holly leveled at his heart.
"One reason not to send you join your dear master," the following words were practically spat with so much venom, they would send a fifth-year Gryffindor-Slytherin potions class cowering behind their cauldrons, "on his next great adventure."
The next thing he knew was a foreign presence effortlessly slipping through his Occlumency shields that he arrogantly thought impenetrable after all these years of confronting Voldemort and sometimes Albus Dumbledore.
Harry's POV
Harry leveled his wand at Snape's heart, simultaneously casting a silent wandless Legilemens with his left hand. The effectiveness of this particular sequence of movements never ceased to darkly amuse him. Make the suspect fear for his life and he almost always dropped his shields low for a split second; time enough for a strong Legilemens to slip through.
He still remembered the astonishment of the other two Confessors after the first several almost effortless successes.
Not today though. His mind still slightly woozy after the tremendous effort of calling up almost every echo of the people killed by the read-eyed bastard and reeling with the unreality of finally having got rid of the threat that had been hanging over the heads of the people he loved and his own for almost all his conscious years, he was bracing himself for a task, to him, almost as gruesome as the one he had just accomplished.
Seeing Snape at Voldemort's side, openly fighting Shack after all the years Harry hardly ever knew of his activities other than on the not rare occasions when a new or sometimes older re-created battle potion or poison made an appearance (the very thought of the damage they could have wrought had it not been for the help of a mysterious "Toby" made him shudder every time he thought of his former teacher) nearly exerted the first-ever "Avada Kedavra" from Harry's lips.
Forcing his anger behind the Occlumency shields and once more remembering Dumbledore's will, he Apparated himself and the bastard to this safe-house only Ron and Hermione knew of, fully intending to extract revenge on the man tearing apart his mind before throwing the traitor back to the Ministry for Dementor's Kiss.
The ease with which he passed Snape's shields would have surprised the experienced Confessor had he not already been deathly tired an full of righteous, in his eyes, anger.
The first few moments of in the another's mind had always been the most disorienting in Harry's past experiences. The thick, unnaturally coloured tropical forest of Bellatrix Lestrange's mind, the devastated, without a single rock in sight moor of Pettigrew's, the "atomic bombing site", as he later described it of some other Death Eater's, the vain and empty mansion of Draco Malfoy's and even the quicksand and drowning goo he observed during his visions in Voldemort's didn't prepare him for the immediate recognition he felt of the barren land where he now stood.
Heartbeat speeding up, he remembered a winter day he could spare to a sudden cold in Hermione's house, the warm comforter in the guest bedroom, the steaming hot mug of tea with honey and the fantasy book she lent him.
Now observing the low fence, the sloping grey grounds, the sunless and moonless skies as if forever frozen a moment before nightfall, the silent village down the road with not a light in it's many windows, he heard it again, pounding in his ears, the phrase that caught his attention. "Here, they drink dust", Ged the wizard told his young friend once, in the after-world of Earth Sea.
"Here, they drink dust." Murmured Harry.