There's an insistent, violent tugging in his spine whenever he's aware of Charles. It feels like when General Ross had one of his teams hook him up to the venom cocktail and dig into his back, hands rough and needles jabbed messy and hard, sucking the marrow from his vertebrae. They'd tried for spinal fluid but his shiny new alter ego fought through the makeshift sedation and killed three of their assailants.
(Bruce tries not to think about it, not because it saddens or horrifies him but because it doesn't and he hates the newly named Hulk for the satisfaction that bleeds behind his eyes. But he doesn't, not really. Hulk knows and rumbles and folds inside a cluster of neurons to meditate.)
Hank and Alex readily tell him and Tony and Tasha and Clint about the before while Thor and Loki curl together beneath the open window and pretend they aren't listening. Knowing makes the tug twist into fire, surging up through his thorax and settling somewhere that's suddenly everywhere but his legs and the panic chokes him but his expression and posture remain unchanged.
(Hulk blooms in the curls of his mind and the void between his lower ribs and Bruce feels the ghost of large arms around his entire body, the panic pulled from Charles' memories returning to them and letting him breathe.)
An angry gush of venom slips from between Tasha's lips and her cheeks and eyes go red and Tony watches curiously as it eats through the floor while Bruce watches her dart away with Clint flitting half a step behind. He decides he should help sometime in the after of his inevitable meeting with Charles' spine (and Hulk pushes closer with a wary little sound so Bruce breathes deep and lets him have more room to do the same).
When finally he can't stand it, sitting two down from the man at the table with breakfast spread between and around them, Bruce apologizes to Charles and kneels beside his wheelchair, worming a hand between flesh and leather coated padding.
He sees the middle lumbar vertebra, shattered into pieces barely held by stringy rips of fibrous discs, sharper, sneakier needles of bone embedded into the vulnerable twitch of spinal cord. He wills them free and bursts the nucleus back into being and bubbles the spinal nerves back into shape, regrows nervous tissue and bone while steadily ignoring the agony in his own spine that bites its way down his legs as Charles gasps and starts to feel his own.
He barely manages to completely reform the connection between body and brain before he falls back into the cradle of Hulk's arms, eyes closing as he is put to sleep in a familiar cluster of neurons that feels like peace and smells like Tony Stark.