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I have a crush on my brother’s best friend…
Cullen Mercer is Covington Prep’s golden boy, Mr. Popular, Homecoming King
He’s always been nice to me, doesn’t mind me hanging around when he’s with my brother
So I don’t know why I’m looking at him differently
Don’t know why my heart races when I hand him a water bottle
Don’t know why I think I’m the one to save him…
Yeah, Cullen’s life looks a dream
But I find out it’s not
And then I do something stupid,
And realize I might have just ruined everything between us

Cullen
Sierra is the Covington Chargers’ Water Girl
And she does a great job for the team
But there’s something else—
She sees me as more than just the football captain, the star quarterback
She sees the real me, the only one who does
But there’s a lot of things against us…
My father’s insistence that football is the most important thing in my life
And that Sierra is a junior…
Who happens to be my best friend’s little sister

216 pages, ebook

First published April 12, 2022

115 people are currently reading
387 people want to read

About the author

Kylie Key

42 books125 followers

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5 stars
134 (49%)
4 stars
79 (29%)
3 stars
46 (17%)
2 stars
10 (3%)
1 star
1 (<1%)
Displaying 1 - 27 of 27 reviews
Profile Image for ☠︎︎༒︎✞︎ ѕℓιм ☠︎︎༒︎✞︎ .
1,540 reviews103 followers
May 1, 2022
It was good cant wait for the next book

https://ladiikeiii.wordpress.com/2022...

***Spoilers here and there***

It was good but I keep saying I want a book with Phoenix. I think he’s going to end up liking Emma or some other girl. I think Emma was the girl who helped him in the book with Tennessee and Millie. I can’t remember her name much. I think that’s who it was.

But anyways I enjoyed this book. I kinda forgot all about this series until I saw it when I was browsing my kindle. I got excited. Then forgot who Sierra was 😂 until I read Cullen and I’m like oooooh.

I have to read this book. Glad I did I definitely enjoyed it.

Only thing that bother me was how Cullen dad treated him I was glad when Sierra came into his life fully by helping him. I could tell she had a thing for him from reading Tennessee and Millie book when they where at his house that one time.

She helped him by taking him away from his father meanness and helping him by telling his mom what happened during the time he fell asleep at her house. If it wasn’t for her he wouldn’t have stood up to his dad. I was glad when he finally realized it after that talking Cullen mom had with him and his dad. His dad deserved to her everything Sierra and Cullen mom had to say.

That man was a horrible individual. I was glad when he gotten better and stopped treating Cullen bad
Profile Image for Norah Z.
31 reviews
July 20, 2025
Okay so I actually really liked this book, but to be completely honest the writing was so mid I couldn’t give it more than three stars without feeling like I was lying.
Profile Image for Kylie Key.
Author 42 books125 followers
April 14, 2022
Author comment: This book is for all those girls who crushed on their big brother's best friend! (Yes, I may have!) I loved these characters. They were never even supposed to have their own book, but after meeting them in The Bookworm, they needed to have their own story! Enjoy Sierra and Cullen's story : )
Profile Image for Morgan.
81 reviews2 followers
April 4, 2023
Ahhhh they are so cuteee😍
The way they made their teddies wave at eachother was the cutest thing.

Trigger warning for eating disorders in a way tho?
His dad pissed me off with how strict he was on not letting him eat certain foods
This entire review has been hidden because of spoilers.
Profile Image for Chicken.
446 reviews6 followers
May 14, 2022
Rating: ⭐️ ⭐️ ⭐️ ⭐️

This was a super cute story. I loved seeing characters from before novels and loved the plot of this book. The writing just flowed and the whole story was a nice cleanser before reading other books. I’m excited for what comes next from this author.

I received a review copy and am voluntarily leaving a review.
3,001 reviews44 followers
June 17, 2022
This is book three of the Covington Prep: The Girls We Love series and the main characters are Cullen Mercer, the star quarterback of the football team, a senior and the Homecoming King, and Sierra Huntington, the Water Girl for the Covington Chargers football team and the younger sister of Sawyer, Cullen’s teammate. Cullen has always been around their house, as she has around his at times, since Sawyer and Cullen are best friends. They have all grown up together and Cullen has always been nice to her, but she has had a serious crush on him for ages. Her job as water girl has her in close contact now with him, as she takes the team’s hydration seriously. But now her heart races every time she passes him a water bottle! Cullen seems to be the golden boy and have no problems with his life, but not everything is the same behind closed doors! When Sierra sees something she shouldn’t have, she realises that his life is not a dream and he is being pushed to do so much more than his team mates and his life is very restricted. His father is the coach of the football team and insists on Cullen living his life in a very strict and regimented manner.
Sierra tries to interfere with what is happening to Cullen and to stop what she sees as the worst parts of it, hoping she can save him from the harm being done to him. There is a great weight of expectation on his shoulders as the Chargers are through to the semi-finals of the State Championship. This from a team that only a few years ago, had never even won a game all season! For some of the players, including Cullen and Sawyer, this is their final year at high school and is their time to succeed. When Sierra slips and hurts her ankle during practice one day, Cullen’s feelings for her become clear as he runs to assist her and wants to look after her. She sees Cullen as more than just the football captain, she seems to be able to see the real him, like no one else. Sierra is a junior and his father has a strict rule of no dating during the football season, never mind that she is his best friend’s little sister and that would be breaking the bro code! With the most important couple of weeks coming to a head with intense training for the Championship, there is little time to get over that first hurdle in a relationship. A sweet story of high school romance and a look into the struggles of life never being exactly what you might think they are.
3,492 reviews42 followers
April 14, 2022
The Kid Sister is a sweet high school romance. Sierra is a bit younger than her brother Sawyer and his friends whose football team plays for the state championship this year. She's the water girl for the team and takes her role EXTREMELY seriously. It's not just a matter of filling up water bottles, she keeps track of how much anyone is drinking and who likes what color of sports drinks and otherwise worries about the team. She likes the team spirit speeches of the coach and wants to feel like a part of everything, and of course, Cullen Mercer is there... He is Sawyer's friend and the captain of the team. Somehow Sierra and Cullen wake up to their mutual attraction at about the same moment. But it turns out that Cullen's dad who is the coach of the team is a bit of a nightmare, as he's trying to live his own destroyed football star dreams through Cullen and pushes his son much harder than the rest of the team. He doesn't believe in rest days, is verbally abusive and wants to control every aspect of Cullen's diet and training, even what he does with his friends.

Full disclosure, I am a little older than the target audience, but I enjoyed this nicely written story quite a bit. The characters are sweet and the plot threads come together nicely, it is mostly well edited and an easy read. Apart from the main couple, you get some good friends, an insistent suitor, as well as some snotty cheerleaders (are cheerleaders ever not snotty in high school romances??) Steam level: Kissing.

What I didn't like is the good ole "oh no will her brother let us date" trope which always strikes me as faintly misogynistic. Why don't the hero's sisters or maiden aunts ever get asked to give permission that a girl can take the hero out for ice cream? If Cullen can decide for himself who he likes, then so can Sierra. How is it any of Sawyer's business? Thankfully Sawyer wasn't a jerk about it.

I received a copy of this book from the author and this is a voluntary review.
Profile Image for Lindsy.
699 reviews16 followers
June 3, 2022
The Kid Sister by Kylie Key is the third book in the Covington Prep series. It’s a best friends younger sister high school romance. I always love reading Kylie’s stories because they are relatable and quick reads.
Cullen is a high school senior at Covington prep and plays football. His father is the football coach which means Cullen gets pushed a little harder than the rest of the team.
Sierra is the hydration expert or water girl for the football team. She’s also Sawyers younger sister and a junior. She’s always hung around the boys and enjoyed football because of her brother but now she’s seeing Cullen in a whole new way.
Sierra ends up trying to save Cullen from being pushed too far by his father. I loved how close the families were too each other and that Cullen had somewhere to go when he couldn’t stand his dad anymore. I was glad he was able to stand up to his dad finally and his mom realized how extreme her husband was being. I was excited to see past relationships and characters in this story as well. I wonder if Phoenix is going to get his own story as well or just be a side character.
Profile Image for Rubi.
2,688 reviews14 followers
September 20, 2023
Cute!

Collen and Sawyer are best friends and he is used to having Sierra around. But when his father's treatment of him starts to worry her and she shows her concern, he starts to think of her as more.
With football season taking #1 place in his household, Collen has a hard time having a life outside of that and it starts to be obvious to others too.
He doesn't want to do anything about his feelings for Sierra and back tracks when she makes a move and regrets it. Its cute how he tries to work up courage to talk to her. And I love how Sierra (quite cleverly) does her best to both protect and respect Collen 🥰
I was worried Coach would cross a line, and was sad about it. He'd been so sweet to Millie and other players. But abusers could portray normalcy but are monsters at home. Its a sad reality and honestly, someone should have reported concern for Collen. But the author handled it pretty well, and Coach wasn't a total psycho. Intervention was what he needed to do better by his son.
Loved loved loved this sweet romance and looking forward to Phoenix's story 😍
Profile Image for BookishShay.
97 reviews1 follower
March 29, 2024
cute read

I love this type of trope!!! Finished it in a few hours, it was such a cute read. I loved the relationship between Sierra and her brother Sawyer, and I loved how Cully and the other players weren’t made out to be douchebags (well, maybe other than Red.) it’s refreshing reading about “good guys” as some of the main characters, and with how Cully was firm in his convictions about his feelings for Sierra. Too many times I read the plot of “denying” their feelings and then some plot twist happens that makes them realize they can’t let the little sister of their best friend that they’ve always known, get away; finally confessing their feelings. That plot isn’t always bad, but this was sweet to see they both felt the same way.
Profile Image for Pauline .
558 reviews2 followers
August 13, 2024
Cute YA read set in the world of high school football. Cullen is under a lot of pressure to win state championship especially by his coach dad. Sierra is his best friend's kid sister and also the team's 'water girl'.She has a huge crush on him. What is more, she sees 'him' and the pressure and is determined to have his back. Cullen appreciates her concern and realises she's just what he needs but what about his best friend and his father who disapproves relationships during the season?
Read to see if everything works out.
Profile Image for Michael Burhans.
587 reviews42 followers
April 23, 2022
Exactly what I have come to expect from Kylie Key. An easy-to-read story, filled with characters you come to feel like you really know. Angst, excitement, love, it has all the feels you could want.

This is the kind of book you find yourself putting down a couple of times because you want it to last longer. I find with all her books that I just devour them as a starving man dropped at a buffet. You forget you are reading and you become one with the story.

When I finished, I was sad it was over, but it had left me in such a good mood. Can
t wait for the next one.
Profile Image for Samaira Singh.
238 reviews3 followers
April 1, 2025
It bothers me that the cover doesn't have the right hair colours. He's supposed to be blonde!
I loved every time Tenn and Millie showed up, though I would have liked more Taylor and Max, but I'm hoping that since the next book is about Phoenix, we'll get plenty of them.
My hatred for Red runs so deep, dude just couldn't take a hint!
Sawyer was such an icon, especially with the 'let him worry about it for a while' thing.
This entire review has been hidden because of spoilers.
Profile Image for Gail.
221 reviews2 followers
April 14, 2022
worth the 5 stars

First this isn’t my typical read. It’s very clean teen. It’s also one of the most Adorable books ever. I loved that Ser was Real Dragon Slayer. That Cully was the blonde princess in need of saving. This is just about the cutest darn book. I really just loved it.
Profile Image for Nati.
2,980 reviews17 followers
April 15, 2022
She is only the Water Girl and her big brother’s best friend. He is the football team captain and his focus is winning theState Championship. But Sierra is worried about Cullen and how his father, coach Mercer, makes him train harder. Can she help him without falling for him? Will Cullen finally notice her? A sweet story about first love, family and makimg your dreams true.
Profile Image for Aldyn Hanson.
40 reviews
January 16, 2024
“Sierra was a junior, Sawyer’s younger sister, part of the Chargers squad. I was older, the football captain, a school leader. And it didn’t matter that she’d made my skin sizzle, that my lips craved her, that she held my heart hostage—she was off-limits. Totally off-limits.”

If you enjoy football you’ll enjoy this book.
Profile Image for Meredith.
773 reviews33 followers
April 14, 2022
This book had a great blend of football, forbidden romance, best friend's sister, difficult family dynamics, fun family dynamics and dreams. It's a sweet, easy read that will almost undoubtedly make you smile.
7 reviews
April 21, 2022
The Kid Sister: A Brothers Best Friend Sweet YA & Teen Romance

This book was a great find. I love all the sweet moments between Cullen and Sierra. It was a good book for those who enjoy football and high school romance.
Profile Image for Michaela | Reading in the Heartland.
3,713 reviews81 followers
May 5, 2022
I really enjoyed this best friends little sister romance. It was a fun trope to have in the setting of high school and I have looked forward to reading it. I liked the athletic setting also. I learned some things.
Profile Image for Emerson A..
98 reviews
April 9, 2025
CULLYYYYYYYYY 😭😭😭

I was dying for him during that extra workout session that Sierra overheard. Killed me 😭
But I liked his difficult secret and how he acts like he was ok but how Sierra was able to help save him from that.
The best friend's younger sister trope 😍
They were so cute!
Profile Image for Jeff.
1,637 reviews4 followers
December 8, 2022
Awesome story

I have enjoyed this wonderful heartfelt story of Cullen the star quarterback and Sierra the younger water girl on the team.
Profile Image for Luci Taylor.
Author 7 books7 followers
September 21, 2024
Sierra and Cullen were the cutest couple! I loved this book and I can't wait to read the rest of the series!
Profile Image for Cat Kaman.
10 reviews
October 26, 2024
loved the story

Only issue was that some quotes were cut short and it looked like there was more but it wouldn’t show. Great book cute story
Profile Image for Charlene.
280 reviews19 followers
February 4, 2025
This book was SO FUN!! I enjoyed the previous book in the series immensely, but I enjoyed this one more. It was fast-paced and easy to read. I finished it at two AM, and I had important things to do the next day. Why can’t I have an older brother with a hot best friend? I’m such a sucker for this trope, even though I’ll never experience it. It’s so wholesome. I enjoyed how realistic the storyline felt for the age group and the characters. They felt like actual teens in high school who were figuring themselves out and didn’t have everything figured out. I enjoyed all the characters in this book. The cameos from The Bookworm were great! I loved seeing the relationship from that series progress and seeing familiar faces. I’m glad we saw more of the characters and their backstories. Sawyer was so much fun, and I enjoyed learning more about him and his character. I would love to learn more about him. I loved Sierra and watching her gain confidence in herself. I related to her a lot, and she was so easy to root for. I lived vicariously through her. I enjoyed her fierceness and protectiveness. Her character development was done well. I really enjoyed Cullen and all of his depth. I enjoyed watching him stand up for himself and gain confidence. I enjoyed his backstory a lot. It deepened his character and made me understand his motivations more. He was really sweet, especially toward Sierra. 
There were a few kisses.
Displaying 1 - 27 of 27 reviews

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