AU where everyone has a natural current of magic that can influence things around them. Grantaire's manifests as cold (his fingertips leave frost on everything) while Enjolras has a literal aura of warmth, and he glows. Their elements clash so much it hurts to touch each other.
Everyone had a Current. It was part of your identity. You learned to gravitate towards people with whom your Current coexisted well with. The first time Grantaire touched Eponine, she sighed in relief, and he had to stop himself from crying out. He had spent his life with his hands hiding beneath gloves, afraid to freeze anything he touched. But Eponine had asked nicely (for once) and he was obliged to agree. He was curious, after all. The first time they touched, it was like a cool spring breeze. It was the feeling in the air of October, as the leaves are steadily turning orange, and the air is crisp and comforting. They touched often after.
The first time Grantaire touched Bahorel, Bahorel had begun to laugh. They had been boxing, and Bahorel’s arm went to instinctively block R’s movements. His forearm touched Grantaire’s fist. His own Current was one of excitement and intense energy. It coincided well with Grantaire’s, surprisingly. They create a chilled buzz of energy, the feeling you get when you are rushing towards the bottom of a hill on a sled, the cold stinging your cheeks. He refused to admit that the blue left on his forearm was anything more than a bruise, and after, didn’t allow R to wear gloves during matches.
The first time Grantaire spoke to Enjolras, he had felt the heat radiating off of him. It was something R had grown to venerate and detest. His own Current was freezing, leaving his hands perpetually trembling, and lips an odd shade of blue. Enjolras’ cheeks were flushed and he always had a sheen of sweat on his forehead. They were opposites, drawn towards each other while simultaneously detesting their harsh opposition. Grantaire longed to reach forward and cool down Enjolras’ perpetual fever. Enjolras wanted nothing more than to take Grantaire under the fold of his arms, and squeeze until that ghastly shade of blue had escaped from his face.
The first time they touched, Grantaire whimpered. It was painful- a feeling of burning. It was like stepping into a bath run too hot, cold feet burning. It was cold glass against a flame, shattering and cracking upon contact. But it was a warmth Grantaire had never experienced, and a sweet, cool relief that stole Enjolras’ breath from his chest. Their Currents needed the other, and deterred the other. It was an impasse of paradox.
Though, they eventually learned to cherish the slow burn, pushing past it until they could touch with better ease. One finally warming as if comforted by a gentle fire, and the other able to relax and breathe freely under the relief of a cool palm.