I do not own Danny Phantom, but you are welcome to hold me completely and utterly responsible for this idea.
A slim red-haired woman sat curled up in a large stuffed armchair near a glowing fire. She held a large tome on her lap and was carefully reading it, making notes on a pad of paper. In the background she could hear the quiet, soothing sounds of her husband at work. She finished the page she was on, looked up into the fire, and started reflecting on how she'd come to be here.
Jazz had first met the man she'd married while trying to save her fifteen-year-old brother from a ghost's curse. Danny, coughing up massive amounts of ectoplasm and getting weaker by the moment, had given her directions to the one person he thought might have an answer. The man at the end of the map had had the solution, like Danny had hoped, and Jazz had been able to lift the curse with the help of Danny's gothic girl friend (not girlfriend), Sam.
The older girl had visited her future husband several times before leaving for college, because she'd sensed in him a kind, quiet soul like her own, and a keen intelligence and creativity that belied itself. A large draw for her was also the centuries' of information he had at his fingertips, and the calm wisdom he'd gained from it. He'd been surprised for the first few times that she'd arrived, but always acted warmly towards her. He'd seen the kindred spirit in her too.
Jazz had spent the first year of university in a flurry of excitement, homework, and friends. From her extensive study of human psychology, she knew such activities should replace her homesickness. They did, for the most part, but she missed the quiet evenings she'd spent in the company of her brother's ally. There were days she wished she could talk about her theories with him, hear his opinions on any topic, and help with his work, as he'd let her do a few times. The first chance she had upon returning home the following summer, she visited him again. He'd been glad to see her, and they'd talked for hours.
The budding psychologist had left for university again secure in the knowledge that she'd be able to see her now quite good friend whenever she wanted, thanks to a portaportal and a preprogrammed boo-merang stashed in her luggage. She and the ghost visited each other occasionally, and they ended up sharing a lot of their worries and secrets. Their routine continued until Jazz had graduated with her B.A., and the ghost came to the ceremony briefly, making sure to stay as far from her ghost-hunting parents and half-ghost brother as possible.
Somewhere shortly after graduating, Jazz had realized that, despite the pallor and transparency that came with being dead, her friend was not unattractive and that her feelings towards him were more than could be explained by mere friendship. She'd even caught herself thinking of him as her boyfriend a few times, and realized that she didn't mind the thought very much, especially since she hadn't dated since high school. Still, someone falling for a person who'd been dead for centuries would be a field day for any psychologist, and that unnerved her. Bringing the subject of a "much older guy" up with her friends had mostly resulted in reassurances that being true to your heart was better for your mental health than being with someone your own age.
Jazz confessed her love for the ghost the next time the two of them met, and he pulled her close and stroked her head gently.
"It's all right, Jazz. I've felt the same way for a while now."
"You, you have?" Jazz picked her head up from his shoulder and wiped a tear from her eye. The ghost holding her drew her face towards his and looked her tenderly in the eye.
"Yes, Jazz. You're everything I'd want in a woman. Smart, brave, loyal, creative, caring, honest, beautiful... I never thought you'd reciprocate."
By the end of that night, they'd decided that telling Danny about their relationship might be a good idea. Having to avoid a boy who could sense ghosts, and stop him from getting more suspicious at his sister's disappearances, would just make their relationship more difficult, and they both wanted to see where it would go.
Danny, one year into community college, had reacted as they'd expected. He screamed, he yelled, he shook his sister, he attacked the ghost for altering reality, and he eventually calmed down enough to listen to reason and realize that the unconventional couple really did love each other. While still disturbed by their relationship, Danny had promised to cover for them whenever they needed it. He'd also broached the idea that he tell his parents about his half-ghost status now, so that their discovery that their daughter was dating a ghost would come as slightly less of a shock later. With the help of Sam, Danny's girlfriend by that point, Tucker, and Jazz, he pulled it off successfully, and his parents accepted him immediately, as he'd hoped they would after seeing so many battles between his alter ego, Danny Phantom, and other, obviously evil, ghosts.
Jazz and her boyfriend spent more and more time together throughout her master's degree, and the night she'd gotten her second diploma, he'd proposed. She'd accepted instantly, of course, and they'd spent a giddy hour together before realizing that engagement meant telling Jack and Maddie Fenton. After a fair amount of planning and advice from Danny, that had gone well too, though both parents didn't completely get over the idea until after the small ceremony a year later, in the Ghost Zone, with many of the friendly ghosts attending. Danny had been best man.
Jazz, ten years into her marriage, thought back to how handsome her younger brother had looked that day, even if it was nothing compared to the way he'd looked the day he married Sam. Jazz smirked, recalling how Sam had exerted her gothic independence by demanding to be married to Phantom rather than Fenton. (Danny's secret had gone global the year before when he'd stopped Vlad Plasmius and his minions from gaining control of the American government, so they didn't need to worry about strange glances, or Sam's parents.)
Jazz now lived in a Neo-Georgian house in New England and had a well-reputed psychology practice. The townspeople gossiped about why she needed such a large home for herself. Some suggested she just liked old homes. Others pointed out her wedding band and said the house was more than large enough for two. They explained the fact that no one had seen Jazz's husband by stating he was either an invalid or just painfully shy. Jazz was letting them guess.
The woman's reverie was interrupted by a cold hand pressing on her shoulder.
"Penny for your thoughts?" asked a deep, rich voice as her husband moved around her chair to take a seat facing her.
"Oh, just thinking. About us. How we ended up together." Jazz smiled thoughtfully, still halfway into her memories.
"I'm glad we did." His voice was warm and tender. There was a scratching, shuffling noise and the dark-haired ghost held a sheaf of papers out to his wife. "Would you mind looking over this? You're better at the plot stuff than I am."
"Of course. I was done with this anyway," Jazz answered, gesturing to the book of ghost history she'd taken from her husband's library during their last vacation. As she took the latest chapter of a hopefully best-selling novel from her husband, she gave one last nod to her memories.
Who would have ever thought I'd end up with Ghostwriter?
Okay, who thought this was going to be JazzClockwork? JazzVlad? Show of hands...