They can read it in each other's eyes tonight. Leo can smell the acrid hiss of fear-excitement-want hanging around Raph, watching the almost anxious way he spins his sai through the air. He knows Raph can see it in the way Leo's hands flick on his sword hilts, the way he paces anxiously as they try to make their way down the street. 
They're both on edge, slick with sweat and blood from a long, hard fight and the energy needs to go someplace fast, or they'll explode. Leo can feel Raph's eyes burning into his and reaches to take his brother's hand, knowing what he has to do. 
"Go," he tells the others, and Mikey and Donnie are happy to leave, letting Leo lead Raph into the nearest alley. They've barely melted into the safety of the shadows before Raph slams him against hard brick, barely giving Leo time to brace himself and press his legs together before his brother’s hips are flush against his. 
No time for lube, at least not in the place their heads are right now, so Raph just fucks his thighs, groaning and quivering at the pressure of Leo’s muscular limbs, his gore slicked scales. His cock rubs up against Leo’s and Leo grinds back on him with a whimper, hands shaking as they press against the brick. 
He’s killed people with these hands tonight. He’s killed people and maybe he should mourn, but he did it to protect his little brothers, to protect the turtle pressing warm and alive behind him, and he can’t quite bring himself to weep for the dead. 
All he can do is lean back into Raph’s eager, grasping hands, letting them trace every pulse point, rubbing away layers of blood to find the pulse rushing beneath. Satisfied, Raph reaches down for their tangled cocks, rubbing his palm over hypersensitive flesh in a way that brooks no resistance. 
Leo manages to keep his back straight and his legs together even when he comes, churring and squeaking against Raph’s broad chest. He keeps his legs together when Raph comes, too, savoring the rush of spend down his legs and pooling around his feet. It’s brighter than the blood and warmer against his skin, heat and the aftersmell of sex pulsing in the air around them. 
Smells like that shouldn’t make your head clear, but it does. Leo lets himself relax with a sigh, gently disengaging himself from Raph enough to turn around and Raph’s arms around his brother’s shoulders. Raph hugs him back and for a few seconds they stay like in the alley–frozen, intertwined, alive. 
“Come on,” Leo whispers. “Let’s go home.” Raph nods, letting him go enough to follow him down the street. They’ll slip in through the back of the lair, washing off the night’s detritus together.  
Above the fluorescent lights the stars glitter down at them, winking at two lovers heading home through New York’s dark streets.