Before Sarah pulled the trigger, she warned Rachel, 

“Now, although the ray will be recharged in an hour like the other times I won’t be able to change you back for 24 hours. Are you sure you want to go through with this?”

Rachel bit her lower lip, a bit worried about this choice. Being however small she was going to be for the next 24 hours sounded a little scary but she’d come this far so she figured she might as well. She just had one question for Sarah, 

“Ok, just one question? How small will this last blast make me?”

Sarah did a few calculations in her head then answered, 

“I don’t know exactly, but between 5 - 8 inches”.

“That’s the biggest shrink yet”, Rachel said, “but fine. I’ll do it. Is there any chance you can join me?”

“Sorry”, Sarah answered, “one of us needs to be big for safety reasons”

“True”, Rachel replied then added with a laugh “then where will we find a big person? You’re pretty small too”

“Very funny pipsqueak. But I’ll tell you what. I’ll reduce myself to stage one so we’ll be closer in size but I’ll still be big enough to handle any emergencies”, Sarah raised the gun again and pulled the trigger.

Rachel was about to say something when she was engulfed in the beam. From Sarah’s point of view the same thing that happened the last three times was happening again, except that it didn’t go away once the shrinking was done but for Rachel things were a bit different.

While in the light she was more aware of her body getting smaller. It was a strange sensation, she could feel the table expanding beneath her feet while she stood still. She also noticed that her clothes were getting looser. This was weird since they had always shrunk with her before. In a matter of moments she had fallen out of everything but her now massive shirt but even that was gone soon enough. She was going to give Sarah crap for not telling her she’d be tiny AND naked for the next day.
Once she felt the shrinking stop she was expecting the light to subside but it actually got brighter. She started hearing a crackling sound and feeling some pressure on her back. Nothing painful, but uncomfortable enough to make her fall to her knees as it kept increasing. Finally, when she thought she was going to burst, it was gone. The crackling was still there however, and was actually louder, almost painful. She was beginning to worry something was wrong when that too stopped.

She lay there hunched over for several minutes before lifting her head and seeing that the light was finally gone and standing up. When she did she could see Sarah’s face at the edge of the table, looking to be about twice as tall as she was. Before either of them could say anything Sarah stood a large plastic pole next to Rachel that she immediately recognized as a ruler. She looked over and saw a number four just a few inches (to her) above her head.

“Oops!” she heard Sarah’s booming voice from way above, “Sorry, I guess I miscalculated a little. You’re actually just under four inches”

“Miscalculated?!” Rachel shouted up to the giant woman in front of her, “What else did you miscalculate? Will I be like this for a week? A month?” she lowered her voice for this last one, afraid to even say it out loud, “forever?”

She waited for Sarah to reply but she just sat there looking down at her in silence. The only thing she said, was

“oh no. I was afraid of this”
“Hello?! Are you going to answer me? Afraid of what?” Rachel demanded, getting a little irritated at being ignored. She grew even more irritated when Sarah burst out laughing instead of answering.

“What the fluff?!” she sighed at the reminder of her reduced vocabulary, “This isn’t funny. If you fluffed this up, what else did you fluff up?”
She stomped her foot for effect, which she didn’t think Sarah even noticed.

Finally Sarah regained her composure and said, still breathless from laughing so much, 

“I’m sorry. I shouldn’t laugh. I’m sure you’re nervous. Don’t worry, from what I can see everything else worked perfectly. There’s just one thing…” and trailed off as she stood up and left the room, reminding Rachel just how tiny she was when she saw Sarah’s massive form even taller than when she was sitting.

Rachel just crossed her arms and waited for her to return, getting more impatient as she waited.
Luckily she wasn’t gone too long and came back holding a vanity mirror and what looked like Rachel’s phone. She put the mirror on the table in front of her and said, 
“Well? What do you think?”

Rachel took a look and didn’t see any more drastic physical changes to her body, all the previous proportions were the same. She still had tiny hands and feet, medium sized round breasts, and a tiny neck.
When she saw her face she saw that her eyes were still huge, but hadn’t gotten bigger and her nose was as small as it was last time. 
She did notice that her hair was a much more vibrant shade of red, and when she turned her head to the side saw that her ears were pointed.
When she reached up to touch them she felt something else moving at the top of her head. Reaching up, she felt two thin, wirelike protrusions growing out of her head, like antennas. When she lowered her head to see them that’s exactly what they looked like. As she bent down she also noticed a flurry of activity behind her. 
Worried that it might be a spider or something equally dangerous to her, she quickly spun around only to see nothing there. 
Relieved, she started to turn back to the mirror when she saw the movement behind her again.
This time she decided to run instead of turning to see whatever it was that was after her. 

From her position Sarah was enjoying watching Rachel discover her new form when she suddenly started running toward the other end of the table at a much faster speed than she expected. She got quickly to be there in case she fell but was too late, in Rachel’s panic and lack of understanding of her new abilities she reached the edge and went right over before she even knew what had happened.

As Rachel was falling, thoughts of what Sarah was going to do for her funeral came to her. Was she going to be able to restore her so she could have a normal one? Or was she just going to get a shoebox and stuff her in that? “Who am I kidding?” she thought to herself, “a shoebox is way too big for me. Probably a cigarette box. Eww, I’m going to be stuck in a cigarette box for eternity.” And then she wondered if she’d even have a funeral. Would she want people to see her like this? Would Sarah just flush her?

It was around the thoughts of being flushed when she realized she wasn’t falling anymore. She looked down expecting to standing in Sarah’s hand even though she didn’t feel anything under her feet and saw that there was nothing there. She was somehow hovering in mid-air. That’s when she realized there was a strong breeze and a buzzing sound coming from behind her.
Rather than face a repeat of last time, she slowly turned her head and saw that the breeze and buzzing, and likely whatever it was she thought was chasing her, were all coming from the new pair of wings she now had.
Just as she made this realization she saw Sarah’s knees come into her view then watched as the giantess lowered herself until they were face to face.

“I’m so sorry”, she said, “I should have warned you. Well, surprise! you’re a fairy now”

Rachel had a hard time staying mad at her after hearing that. When they were little (well, in her case the more accurate word would be younger) they used to always talk about how cool it would be to be fairies. Flying around wherever you want with nothing to hold you down and being small enough to hide anywhere you wanted. She has some many questions for Sarah but before she could ask any, she pointed up and said, 

“Please, land on the table near your phone. I need to explain one more thing to you”

Rachel was surprised at how easily flying came to her after only a few minutes as a fairy. She quickly flew up and landed on her phone, so fast that Sarah hadn’t even begun to stand up. In fact, it felt like she was just finishing her last word and wasn’t even moving while she was already sitting on the edge of the phone. 
When she settled down she saw Sarah move again and actually heard the last syllable of the “you” she had just said. Sarah looked around, as she stood up and when she saw her new fairy friend sitting there like she’d been waiting for a while she said, 

“Wow, I knew you’d be fast but I didn’t realize you’d have super speed”

Rachel asked her how fast she moved but was ignored,

“So, what I was trying to say before is that I had to do something to your nervous system and motor system for you to be able control those wings and your flight. I’m not sure if you’ve noticed, but you um, can’t talk anymore. I’m sorry, this was only a hypothetical possibility, I didn’t think it would actually happen”

“What do you mean, I can’t talk?” Rachel asked, “I’m talking right now”

Sarah looked down at her and replied, 

“I’m guessing you’re saying something about you talking right now. Here, listen to this recording I just made of that talking”

She held out her own phone and pressed the play button. After Sarah’s part, all Rachel could hear was what sounded like tiny little bells tinkling. She kept waiting for her voice to come but it never did.
Sarah noticed this and told her that that tiny tinkle sound was her voice. She had to make room in her brain for all the flight ability and that meant using parts of her brain that controlled her speech. She assured her yet again that it was all reversible and although she believed her, Rachel was pretty upset about this.

“You wiped out my ability to talk!” she shouted, forgetting that her words meant nothing to her now. She felt herself rising and realized she was now hovering in Sarah’s face but didn’t even think about that as she kept yelling at her. Finally, after several minutes of this she slowly lowered back to the table and sat back on her phone with her head in her hands.

Sarah, feeling very bad about this, pointed to the phone and said, 

“That’s why I got your phone. If you want to say something, just type it on the keypad”

Rachel got off her phone, and after several attempts at swiping with one hand, realized she was so small she needed two and got her phone unlocked and the message app started. When it was open she reached down to the keys, and again needing two hands, typed:

“WTF”

Sarah apologized some more but Rachel was back to typing,

“will this really be 1 day?”

“Yes”, Sarah assured her, “that I’m positive about”

“sure?” Rachel typed.

“Absolutely” was the reply.

Rachel thought for a moment then typed, 

“not talking sucks but still cool ”

Sarah was glad she was still happy. She saw Rachel typing some more, when she looked down the screen said, 

“how bout clothes”

Sarah had that part covered at least, she reached into her pocket and pulled out a small cloth napkin. She had cut it the day before to fit a person between 5 - 8 inches tall but figured it would work for a 4 inch one as well. She handed it to Rachel, who didn’t seem super happy with wearing a toga but made do with what she had. When she had it on, she bent down to the phone and said, 

“well how do i look?”

“You look the cutest you have all night”, and she lifted Rachel to her face and gave her a big kiss that covered her whole head then placed her back down.

“your turn” Rachel typed

Sarah asked what she meant and when Rachel pointed to the ray she remembered her promise to get smaller for her. She looked at her the clock and saw that there was still 10 minutes left. She told Rachel to have fun flying around while she got a few things ready, then left to head to the bathroom as she saw a tiny blur zipping around the kitchen then zoom by her head and disappear into the living room.
When she got into the bathroom, Sarah filled the bathtub with warm water and placed a small beach towel and washcloth on the floor in front of it. She also went into the medicine cabinet and brought any emergency first aid supplies she thought she could use down and put them under the sink. 
When that was done, she went into the kitchen and got all the sweets down off the top of the fridge and placed them on the table. She looked around to make sure she had thought of everything, then when she was sure she confirmed that an hour had passed and set the ray on the counter with a delay on the trigger, stood in front of it, and closed her eyes.

When she opened them again she saw that she could just barely see over the top of the counter. She estimated her height to be around 3 and a half feet tall, which made sense since she was smaller to begin with. 
She started out looking for Rachel but was distracted by the best thing she had even smelled in her life coming from the table. After she had climbed onto a chair she opened the frosting jar and dug into it her with small fingers. Despite her small size, she managed to eat a quarter of it in no time and was planning on eating more when she saw Rachel, looking slightly bigger but still tiny, land in front of the pile of sweets.

To Rachel, Sarah was still a giant obviously, but a less impressive one now. Especially now that her features were more out of proportion and cuter. She went over to the jar of frosting this mini giant was eating out of and climbed the side to get some herself. 
When saw Sarah saw this she laughed and picking her up, pulled her toga off, and stuck her in the frosting.
Standing up to her waist in chocolate frosting, which in her current state was like a drug to her, was more than she could bear and she reached down and began scooping large handfuls into her mouth as fast as she could. Which with her speed made Sarah seemingly freeze mid bite while little Rachel kept eating until it was only up to her knees.

When the little blur that was Rachel finally slowed down, Sarah saw that she had eaten way more than she figured such a tiny thing could eat so she plucked her out, her lower body now covered in frosting.
She held her in front of her face and carefully placed one leg in her mouth and gently licked the frosting off. While she did this she could her tiny giggles and tinkling coming from Rachel. There was more when she did the other leg, and even more when she cleaned the rest of her off.

When she was done, she held the naked fairy in hand, panting from exhaustion but looking very pleased, then dipped her in the frosting yet again for another round. 
This went on until the jar was empty and both women were feeling more energetic than when they started.

“Come on”, she said placing the tiny fairy on her shoulder, “We need to get cleaned up”.