Inspiration (comment fic)
Ooh...I couldn't help myself. The following just seemed to jump out of my fingers! *grin*
The scars brought them closer, wounds healing to seal in the Dark, of magic, of lost dreams, of primeval passions. Severus never asked; he simply appeared at Lupin's door, stripped to his skin and dropped the Glamours that hid what the werewolf carved into his body. Lupin never spoke more than ten words at a time when Severus was naked, vulnerable, malleable. Neither one would share this secret with the world, the scars given and accepted were theirs alone, something neither Voldemort nor Dumbledore could understand.
As the blood dripped from Snape's carved body, Remus felt its warmth against his golden skin, soaking in and sparking off his magic. He twisted his hips and plunged back into the grasping, suffocating heat that fed off all that blood. He dipped his fingers into the red, red wine of Severus Snape's veins and traced ancient symbols over his slashed chest and arms. "My marks never fade, Snape!" he growled. "They are ours...forever."
Severus threw his head back and moaned. If this was punishment for his sins, he vowed to sin more often! "More..." he begged prettily. Lupin's long nails raked over his buttocks and his wish was answered.