Happy ending version:
When Batman woke the next morning, all he can feel is a throbbing pain by his side.
"You up?" Hearing the voice of the Joker, Bruce snaps up, temporarily stopped by the searing pain of stitches tearing into his flesh.
"Hey, you'd reopen the wound, ya know!" Joker blinks at Bruce, most of his makeup washed off by-
is that tear streaks?!
The Joker pokes at Bruce's face with an ungloved finger, looking oddly sad and innocent.
He didn't pull back when Bruce cups his face and pulls him into a kiss. A soft kiss, but one so full of emotion.
Bruce is not sure if his heart would explode when Joker kisses back, lightly at first but then so desperate that it breaks his heart and he clings back.
'I will never let go.'
When they finally break apart for air, Bruce opens his mouth to explain, that he is so sorry and that he loves him, so much that-
"Ssh...I know." Joker presses a finger to his lips, and smiles. It's the first real smile the Bruce has ever seen and it lights his world.
"Lets go home." Bruce tells the Joker but they stay where they are.
Gotham, home.
And not to be clichéd, but they lived happily ever after.