Sirius hesitated when he saw the expression on James' face; he couldn't help himself. None of this was ever supposed to have gone this way. Their lives were supposed to be so much better than this. But this mess was what they had and Sirius had long since come to terms with the fact that he wasn't just going to throw everything away because it wasn't perfect. He steeled himself for whatever James was about to say.
Yet, he was surprised when it was an almost forgotten nickname. The word hit him like a suckerpunch, because even Remus didn't call him that anymore. It was a right he had thought himself permanently stripped of. The moment it left James' lips, Sirius' resolve to try and handle this like an adult dissipated.
"Jamie," Sirius replied instantly. "Prongs."
He closed the distance between them, grabbing at James. He threw an arm around James' shoulder and hugged him tightly, burying his own face in against James' shoulder. He shut his eyes, concentrating on what was happening, because he couldn't help but be constantly reminded of how close he had been to losing this forever. And so maybe this time was the last, but he was going to cherish it then. His fingers fisted in the back of James' robes and he could feel James' glasses cutting into the side of his face.