Animal Shifter AU where Bruce's form is a bat, and when he finds out Jason's identity he gets so overwhelmed by emotion he shifts and just squeaks up a storm, calling out desperately for his little miracle boy, and Jason who is so filled with rage and hate is snapped out of the pit haze by seeing such a small creature so clearly distressed. He's still angry, still bitter, but he can't bring myself to hurt his father.
Jason, who is furiously threatening to kill Bruce even as he cradles the small bat to his chest, who is plastered so firmly against Jason's chest plate it's as though he's trying to fuse into Jason's skin. Bruce doesn't shift back even when he's able to, when he's not overwhelmed anymore, because Jason will leave again when he's a person, and Jason takes the time to air out all of his grievances while Bruce can't talk back to defend himself.
Jason ends up going to a safehouse and Bruce stays with him for like two days, and by the end of it Jason feels significantly better because his dad is being so clingy and affectionate that it reminds him of the happiest years of his life, spent in Wayne Manor. His anger burns out quickly, and he can't bring it back. When Alfred tracks his ass down, not knowing who the Red Hood is yet but furious because he thinks Jason killed or took Bruce, he damn near shoots down the door of Jason's safehouse to see Jason reading on his couch, Bruce (as a bat) curled up on his shoulder and nuzzling his little head into the underside of Jason's jaw.
And obviously Jason can't deny Alfred anything so he gets dragged back to Wayne Manor where Dick and Tim await, losing their minds with worry.
