"3...2...1... HAPPY NEW YEAR!" There was plenty of cheering at the Zephyr house as the clock finished counting and the new year had begun. It was a little bit fuller than usual. For one thing, the eldest son, Mark, had come home for the holidays. But probably the more important addition was Mercy Elaga being there as Zack's new girlfriend. The two of them certainly took up quite a bit of space, even with their wings folded.
"Well, it's past midnight, time for bed," said Mr. Zephyr.
"But the night's just getting started," said Zack.
"Look, you may be a bat now, but that doesn't mean we have to be nocturnal too," said Mr. Zephyr.
"You don't actually need to stay up all night, do you?" asked Mrs. Zephyr.
Mercy shrugged and said, "Day and night are really the same to me. I just need a minimum of six hours of sleep, whichever time it is."
"Well, you can stay up, but don't you keep us up," said Mrs. Zephyr.
"Especially with all the squeaking," said Mark.
"I don't squeak," said Zack in annoyance.
"Your bed does," said Mark. Zack responded by throwing a pillow at him. Mercy was more amused than annoyed. She wasn't against the idea of having some late-night fun with Zack. He's proven himself to be a good lover after his conversion...
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Zack had been attracted to Mercy since he first met her, when she helped unlock the safe found in their attic that was full of treasure. But it wasn't just the face that she made him rich or her curvy Animalian body that drew Zack to her. He found her backstory of reformed thief very interesting, even if she didn't choose herself to go straight.
Mercy was flattered by the attention, but she made it clear that she wasn't a woman easily won. Even so, Zack remained persistent, never really pushing Mercy or making it seem like he was stalking her. He just kept inviting her to family events or going to see movies. Of course, the pandemic severely limited the options for going out. But Zack did keep in regular contact, sometimes calling her for a little conversation.
Mercy did eventually soften around Zack. His tenacity did show he actually cared about her, not just because she was a sexy woman. Probably another reason she softened towards him was because of loneliness. She may have been largely forgiven for her past crimes, but she was still a criminal to some and not a lot of people wanted to talk with her for purely personal reasons. And there weren't a lot of bat Animalians in Lyre, particularly not any other black mastiff bats. There was Bruce, the bat Animalian who helped Mercy learn how to fly with her new wings, but he didn't seem interested in a romantic relationship.
Of course, Mercy still had to talk to Zack's parents about her intentions. Even if Zack had just turned 18, he was still their son. Zack no longer being human seemed like a secondary concern compared to Mercy's reputation. No good parent would want their child being in a relationship with a criminal. And yet, Mercy's shown herself to be a responsible woman despite her former career. She has earnestly stopped her thieving ways and was helping out the police for genuine altruistic reasons, rather than being forced to. Lyre was a rather crime-free area, but Mercy did show she was a law-abiding citizen now. So she got their permission to convert Zack.
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It was Christmas Eve, close to midnight, and Zack was in bed, not quite able to go to sleep. He might be too old to believe in Santa, but he still got excited for Christmas. But he wouldn't be dreaming of sugarplums tonight. He heard a tapping at the window. He ignored it at first, thinking it might be a bird, but it became more insistent. Zack rolled over to look to see a dark shape outside the window. He almost freaked out until he heard Mercy's voice outside saying, "Please let me in, it's very cold out here."
Zack quickly opened the window and let her in. "Mercy, what were you doing outside my window at this time of..." His train of thought derailed once he turned on the lights. He now saw that Mercy was wearing little more than some holiday-themed lingerie. The red and green contrasted a lot with her black fur. And two particularly noteworthy features were the large red bows between her breasts and on one of her hips. It seemed pretty clear that when untied, they would leave her completely exposed.
Mercy shivered as she rubbed her arms for warmth. "Note to self: fur alone doesn't provide enough warmth," she said.
"Uh, Mercy?" asked Zack.
"Ok, I didn't think the entrance all the way through, but that isn't the important part, right?" asked Mercy.
"What are you doing here?" asked Zack.
"Isn't it obvious? I'm your Christmas present," said Mercy.
There was a pause before Zack asked, "Is this a prank?"
"Far from it," said Mercy, "I told you once before that I wasn't an easy woman to win over. But you succeeded nonetheless. And please don't ask me to get into more sappy detail. And I'm ready to make you my mate. If you still want me."
"Of course I do. Why wouldn't I want you?" asked Zack.
"In that case, you'll need to take off your shirt for this part," said Mercy. Zack offered no resistance as she pulled his shirt off. After that, she planted a big kiss on his lips, getting her tongue into his mouth.
Zack soon started feeling strange. His ears prickled as they started to grow larger. His body hair was becoming thicker before turning black. His face started pushing into Mercy's as he began developing his muzzle. The nails on his hands became a little sharper as they became claws. His feet grew a little longer and the toes were longer too, allowing to grab at walls and ceilings more easily. Then Zack doubled over as his back started aching. New extensions started growing from his shoulder blades and the base of his spine. As a black mastiff bat, his tail was noticeably longer and less bound to his membranes. Mercy massaged Zack's back, which reduced the ache of having his wings grow in.
Zack looked back up at Mercy, his large ears parting through his dusty brown hair and framing his face, particularly with how they partially joined with his eyebrows. "That was more uncomfortable than I thought it would be," said Zack.
"It'll get better," said Mercy. Then she hooked her thumbs into his waistband. "You'll want to take off your pants for this next part," she said in a husky tone. Zack didn't offer that much resistance when she pulled down his pants and underwear. Under most circumstances, he'd be intensely embarrassed to be naked in the presence of a woman. But his new Animalian hormones were quick to respond and he could smell how much she wanted him. He reached up and undid Mercy's bows. Her lingerie fell open, exposing her breasts and crotch.
Mercy pushed Zack onto his bed. "Don't lie down just yet," said Mercy, "It'll take time to get used to your new wings." But she still crawled on top of him, hovering her snatch over his newly transfigured cock. "You want to stuff my stocking now?" she asked coyly.
Zack placed his hands on her hips and pulled her down. He entered her easily enough. Mercy wasn't a virgin, she had a few liasions in the past, quite often with temporary business partners. But it was different now. Zack obviously gained some length with his first dose and his second dose was going to add a little more.
At 18, he was already almost full-grown, but he still had a few years before his prime. As Mercy put her hands on his shoulders, she could feel them widen a little more. His thin chest was filling out with more muscles, developing particularly strong pecs to enable his flying capability and hard-cut abs beneath them. She moaned as Zack started to fill her more before letting out a delighted squeak as she felt him latch onto one of her nipples. The growing bat man was drawing deep from her milk reserves as he put on more height. Mercy put her arms around his broadening back for support as he pumped harder. It would have been too short if it wasn't for the fact that just growing inside her put Mercy close to the edge. Then the two bats moaned as Zack pumped his first load into her.
Zack gasped for breath before looking his new mate in the eyes. "So, how much longer do you want to stay up?" he asked, his voice a little deeper.
"As long as you want," said Mercy before kissing him again. She had a feeling that she made this his best Christmas yet.