Disclaimer: I don't own Batman Beyond, I make no money writing this, blah, blah, blah.

Genetics-:-

The computer screen, an uncomfortably bright light shining through the batcave and nearly blinding the back of his eyes, shows the information he requested and yet, Bruce still can't quite wrap his head around it.

Terry probably understands it even less, but he understands that this is really important to Bruce and doesn't say a word as the old man scrolls through the data, the wrinkles around his mouth turning in and out with his frowns. Forty-some years wondering what happened to the one that got away had come to a head at Barbara calling and telling him the news.

Harley Quinn was dead. In the morgue. Murdered.

Bruce didn't bother to look at Terry as the young man left him to himself to think about the events. Bruce acknowledges the sound of the grandfather clock opening and closing, but that's all and he is drawn back to the pictures Barbara sent. Some were of Harley, dead in the body bag with that jagged, horrible line across her throat. Some pictures showed the scene of the crime; a little house in tatters from Harley no doubt being thrown around rather like she had been when she was alive, her blood on the walls in words rather similar to Terry's father's crime scene. Mocking laughter written in liquid that took forever to come off. A couple pictures revealed the granddaughter that had called it in, seeming out of it and scared in one of the waiting room chairs at the police station, a coffee cup in her hands.

In another link attached to the pictures was a chatter of four DNA profiles. Harley's and the granddaughters; the one that had called it in, Deidre, and the one who hadn't answered the police's phone calls, Delia. And Joker's.

He hadn't been able to find Harley's first child's information, but it didn't matter.

The young girls' DNA was almost completely like Harley's, only with a few characteristics of Joker himself. From all the things in both the Clown Prince's blood and Harley's own, it made for interesting abilities in their offspring. They were immune to poison, to most diseases, they were fast healers (or at least he could assume they were), they were destined to have female offspring because of some defect from Harley's side of the genetic code, would almost certainly look like Harley when they reached maturity (as if they didn't already), as would any children they had, and actually seemed to be Harley's clones. Unfortunately, Joker's DNA was in there and he could see some problems developing in the elder twin, Delia. Ones that would produce pale skin, darker hair and, if it got bad, his homicidal mania.

Heaving back in his seat, Bruce rested his head against the chair's headrest and felt himself shudder a little bit in… something.

His chest hurt, but it wasn't from his medically diagnosed heart problems, it was from grief. Grief that he should not feel for Harley Quinn, but he did because—for God's sake—she, of all of his Rogues, did not deserve to die like that. Aside from maybe Selina, Harley was the good one. The kind one. The one that, as far as he could find, had never actually killed anyone herself and apologized even, for her actions and got the hell out of the shitty hole she had planted herself in because of Joker.

She got out and had a child—had grandchildren—and raised them all by herself. She did not deserve to die like that.

Ace got up from where he had been just staring at Bruce for the past hour and nosed his palm, a tiny whimper, like when he was a puppy, echoing around the cave. The softness of his fur and the wet leather feeling of his nose brought to mind hyena's he had paid for when no dognapping from the zoo had occurred in the weeks following Joker's death. They had died years ago, of course, but Bud and Lou had sired many puppies and there were still a couple of their great-great-grandchildren at the zoo, always in pairs, never practicing fratricide. Not like other hyenas—and there was that pain in his chest again. And sting in his eyes.

Patting Ace on the head, he rubs his eyes and they wander over to the picture of the granddaughter. If he aligned a picture of Harley right next to that picture of that little girl, it would probably be like looking at Harley even before he had met her the first time. She was pale, much too pale to be healthy, and that probably came from Joker and that thought made Bruce grit his teeth painfully. But…the first, and really only, Dark Knight noted that she was too timid looking and small and so obviously heart-broken and in shock to ever be Joker.

He had Delia's records on file from Barbara sending them to him, like everything else, and thought… He had read them through and through and this ever-present fear had developed in him since then that Delia had more than enough potential to be the next Joker. Compared to the younger twin, Delia's record was longer than his arm and that was just for things while she was allied with the Jokerz gang. It got longer from when she was younger.

He was worried.