Untamed Aggression

by Matthew Dante

Marcus
39, tough, headstrong, and leader of the Shadow Vipers.

Being the leader of a biker gang is like being a father on steroids. You’ve got to be smart, ruthless, and able to wrangle a pack of overgrown, testosterone-fueled, man-children who can’t seem to go a week without causing chaos. The number of times I’ve had to clean up their messes is ridiculous.

As if that wasn’t enough, now I’m playing babysitter to Mr. Never-Shuts-Up. I literally threw him in the trunk, and the guy still continued screaming at me! The mouthy little menace is going to be the death of me.

I should just let that serial killer get him.

But when he looks at me with those eyes… I know I’m a goner.


Gavin
24, Influencer by day, hopeless romantic by night.

I’ll admit it. My taste in men hasn’t exactly been stellar. Case in point? My last date tried to murder me.

Oh. And he happens to be a serial killer.

Yes, leave it to me to swipe right on the Valentine Killer.

So, naturally, the universe decided that the safest place for me is under the protection of a ginormous, six-foot-four, permanently scowling biker who looks like he eats danger for breakfast.

He doesn’t smile. He doesn’t flirt. So, of course, I’m head over heels attracted to the guy.

As I said, my taste in men can’t be trusted.

Genres: M M Romance

316 pages, Paperback

Published May 7, 2026

About the author

Matthew Dante is a Canadian Indie Author who writes MM Dark Romance and MM Contemporary Romance. He is an avid reader, world traveler, lover of all things Marvel and DC, and a romantic at heart.

You can follow Matthew on:
Instagram at MatthewDanteBooks
Facebook at Matthew.dante.73

Reviews

[Betty Loves Books Galore · Rating 5 out of 5]

This is a bodyguard romance, featuring Gavin and Marcus, and is book four in the Bikers Of Mayhem series.

After escaping a serial killer, Gavin is forced to hide out with Marcus, the tough leader of the Shadow Vipers biker gang. Even though they constantly clash, and Gavin talks non-stop, Marcus can’t help but fall for Gavin.

The book was a great mix of danger, chaos and two opposites falling for eachother. Gavin and Marcus start off with an hilarious meet-cute, and their chemistry is intense, with plenty of banter and forced proximity goodness. I loved the found family biker gang and I’m loving this series.

Things to expect in this book are:
Book 4 in series
MM romance
MC club / biker gang
Bodyguard x client
MC president x influencer
Age gap (39 / 24)
Size difference
Opposites attract
Hurt / Comfort
Serial killer survivor
Forced proximity
Only one bed
Flirting & protective
Platonic cuddles
Caretaking
Carries him
Bi awakening
Spicy times
Kidnapping & rescue
Revenge plan
Found family
HEA

[Eric · Rating 5 out of 5]

I don’t know why I love these Viper boys so much but fuck I do. Started the book last night and finished it today.

Marcus and Gavin were hella cute. I’m here for a giant biker with a heart of gold (and a giant 🍆) ... Yes, please.

Also, I am here for Lucas (book one) going full murder twink again. 😍😍

🌶️🌶️.5
⭐️⭐️⭐️⭐️ ⭐️

Breeding kink
Touch him and 💀
Fight against a Cereal Killer
Bi-awakening

[Linda Brown · Rating 1 out of 5]

Sorry, but this was really disappointing for me. I’ve been following this series from the beginning but this was a total let down! The storyline was completely unconvincing. Gavin was a total jerk and very immature for his age. There was no chemistry between him and Marcus. I almost didn’t finish at around fifty percent when the ‘daddy’ thing started. I’m sorry‘daddy’ kink is a big no, no for me and I actually felt sick when Marcus said “take all of daddy’s meat” 🤢

[Stacey · Rating 5 out of 5]

𝑶𝒏𝒄𝒆 𝒂 𝒑𝒓𝒐𝒕𝒆𝒄𝒕𝒐𝒓, 𝒂𝒍𝒘𝒂𝒚𝒔 𝒂 𝒑𝒓𝒐𝒕𝒆𝒄𝒕𝒐𝒓. 𝑴𝒂𝒓𝒄𝒖𝒔 𝒘𝒐𝒖𝒍𝒅 𝒃𝒆 𝒘𝒉𝒂𝒕𝒆𝒗𝒆𝒓 𝒊𝒕 𝒘𝒂𝒔 𝒕𝒉𝒂𝒕 𝑮𝒂𝒗𝒊𝒏 𝒏𝒆𝒆𝒅𝒆𝒅. 𝑨 𝒑𝒓𝒐𝒕𝒆𝒄𝒕𝒐𝒓. 𝑨 𝒑𝒓𝒐𝒗𝒊𝒅𝒆𝒓. 𝑨 𝒑𝒆𝒓𝒔𝒐𝒏 𝒕𝒐 𝒍𝒊𝒔𝒕𝒆𝒏.

Matthew Dante's Bikers of Mayhem series just gets better and better!

Untamed Aggression is a thrill ride from start to finish.

Filled with great characters, an edge-of-your-seat storyline, perfectly combined with comedic timing, crazy antics - particularly from the sweet but psycho, Lucas 😆 - and plenty of steam, I absolutely loved this book!

I've been waiting for Marcus's story since the start of the series. He's this gruff president of a motorcycle club, but with a sweetness inside as he protects his crew and those who need help.

Marcus was quick to help Lucas when he first arrived, and he is the first to act when someone needs protection. He has long been a father figure and adores his brother, Ace, often hilariously threatening his brother-in-law, Blade, but he has no one to call his own.

Enter Gavin to solve that and bring love to this grumpy guy with a heart of gold.

Gavin is such a sassy little sweetheart, but it broke my heart how frightened he was 🥺

After managing to escape a notorious serial killer, when his date turned into a nightmare, Gavin is sent to the Shadow Vipers for protection, where he moves in with Marcus.

Gavin soon seeks comfort for his nightmares in Marcus's bed, stirring feelings in the burly biker that he has never experienced before.

𝑰𝒕 𝒘𝒂𝒔 𝒃𝒆𝒄𝒐𝒎𝒊𝒏𝒈 𝒉𝒂𝒓𝒅𝒆𝒓 𝒂𝒏𝒅 𝒉𝒂𝒓𝒅𝒆𝒓 𝒕𝒐 𝒌𝒆𝒆𝒑 𝒉𝒊𝒔 𝒉𝒂𝒏𝒅𝒔 𝒐𝒇𝒇 𝑮𝒂𝒗𝒊𝒏. 𝑻𝒉𝒆 𝒅𝒓𝒂𝒘 𝒉𝒆 𝒇𝒆𝒍𝒕 𝒇𝒐𝒓 𝒕𝒉𝒆 𝒚𝒐𝒖𝒏𝒈 𝒎𝒂𝒏 𝒘𝒂𝒔 𝒈𝒓𝒐𝒘𝒊𝒏𝒈 𝒔𝒕𝒓𝒐𝒏𝒈𝒆𝒓 𝒆𝒗𝒆𝒓𝒚 𝒅𝒂𝒚 𝒕𝒉𝒆𝒚 𝒘𝒆𝒓𝒆 𝒕𝒐𝒈𝒆𝒕𝒉𝒆𝒓.

Marcus was always committed to protecting Gavin, but I loved how quickly he switched into thinking of Gavin as 'his' boy, and his protectiveness went up to new levels.

“𝑾𝒉𝒂𝒕’𝒔 𝒕𝒉𝒆 𝒃𝒊𝒈 𝒅𝒆𝒂𝒍? 𝑺𝒐 𝒘𝒉𝒂𝒕 𝒊𝒇 𝒔𝒐𝒎𝒆𝒐𝒏𝒆 𝒇𝒐𝒖𝒏𝒅 𝒎𝒆 𝒂𝒕𝒕𝒓𝒂𝒄𝒕𝒊𝒗𝒆? 𝑰𝒕’𝒔 𝒏𝒐𝒕 𝒍𝒊𝒌𝒆 𝑰 𝒔𝒂𝒊𝒅 𝒚𝒆𝒔 𝒐𝒓 𝒕𝒐𝒐𝒌 𝒉𝒊𝒎 𝒖𝒑 𝒐𝒏 𝒉𝒊𝒔 𝒐𝒇𝒇𝒆𝒓.”
“𝑺𝒕𝒊𝒍𝒍. 𝑯𝒆 𝒔𝒉𝒐𝒖𝒍𝒅 𝒌𝒏𝒐𝒘.”
“𝑲𝒏𝒐𝒘 𝒘𝒉𝒂𝒕?”
“𝑻𝒉𝒂𝒕 𝒚𝒐𝒖’𝒓𝒆 𝒎𝒊𝒏𝒆.”

Gavin also seemed to be able to get anything he wanted from the fierce biker; a place to turn when his fear took over, someone to hold in bed each night, and the puppy of his dreams. Don't underestimate the lengths Marcus will go to for those he loves. He's just who everyone needs to take care of them 🫠❤️‍🔥

“𝑩𝒖𝒕… 𝒘𝒉𝒚 𝒅𝒊𝒅 𝒚𝒐𝒖 𝒃𝒖𝒚 𝒎𝒆 𝒂 𝒑𝒖𝒑𝒑𝒚?” 𝒉𝒆 𝒂𝒔𝒌𝒆𝒅, 𝒔𝒕𝒊𝒍𝒍 𝒄𝒐𝒏𝒇𝒖𝒔𝒆𝒅 𝒂𝒏𝒅 𝒐𝒗𝒆𝒓𝒋𝒐𝒚𝒆𝒅 𝒃𝒚 𝒕𝒉𝒆 𝒈𝒆𝒔𝒕𝒖𝒓𝒆. “𝑪𝒂𝒖𝒔𝒆 𝒚𝒐𝒖 𝒔𝒆𝒆𝒎𝒆𝒅 𝒍𝒊𝒌𝒆 𝒚𝒐𝒖 𝒄𝒐𝒖𝒍𝒅 𝒖𝒔𝒆 𝒂 𝒃𝒊𝒕 𝒐𝒇 𝒄𝒐𝒎𝒇𝒐𝒓𝒕. 𝑷𝒆𝒓𝒉𝒂𝒑𝒔 𝒕𝒉𝒊𝒔 𝒍𝒊𝒕𝒕𝒍𝒆 𝒈𝒖𝒚 𝒘𝒊𝒍𝒍 𝒉𝒆𝒍𝒑 𝒚𝒐𝒖 𝒕𝒉𝒓𝒐𝒖𝒈𝒉 𝒔𝒐𝒎𝒆 𝒐𝒇 𝒕𝒉𝒆 𝒕𝒓𝒂𝒖𝒎𝒂 𝒚𝒐𝒖’𝒗𝒆 𝒇𝒂𝒄𝒆𝒅 𝒕𝒉𝒆𝒔𝒆 𝒑𝒂𝒔𝒕 𝒇𝒆𝒘 𝒅𝒂𝒚𝒔.”

I loved the friendship Gavin developed with Ace and Lucas; these three quickly became besties.

And as always, the Shadow Vipers were there when one of their members needed them to jump into action.

“𝒀𝒐𝒖 𝒕𝒓𝒖𝒔𝒕 𝒎𝒆, 𝒓𝒊𝒈𝒉𝒕, 𝑮𝒂𝒗?” 𝑴𝒂𝒓𝒄𝒖𝒔 𝒂𝒔𝒌𝒆𝒅, 𝒉𝒐𝒍𝒅𝒊𝒏𝒈 𝒉𝒊𝒔 𝒃𝒓𝒆𝒂𝒕𝒉 𝒂𝒔 𝒉𝒆 𝒘𝒂𝒊𝒕𝒆𝒅 𝒇𝒐𝒓 𝒂𝒏 𝒂𝒏𝒔𝒘𝒆𝒓.
𝑮𝒂𝒗𝒊𝒏 𝒏𝒐𝒅𝒅𝒆𝒅 𝒊𝒏𝒕𝒐 𝒉𝒊𝒔 𝒄𝒉𝒆𝒔𝒕 𝒂𝒔 𝒉𝒆 𝒄𝒍𝒖𝒏𝒈 𝒕𝒐 𝒉𝒊𝒎 𝒘𝒊𝒕𝒉 𝒂 𝒔𝒕𝒓𝒆𝒏𝒈𝒕𝒉 𝑴𝒂𝒓𝒄𝒖𝒔 𝒉𝒂𝒅 𝒏𝒆𝒗𝒆𝒓 𝒇𝒆𝒍𝒕 𝒃𝒆𝒇𝒐𝒓𝒆.
“𝑨𝒏𝒅 𝒚𝒐𝒖 𝒌𝒏𝒐𝒘, 𝑰 𝒘𝒐𝒖𝒍𝒅 𝒓𝒂𝒕𝒉𝒆𝒓 𝒅𝒊𝒆 𝒕𝒉𝒂𝒏 𝒍𝒆𝒕 𝒂𝒏𝒚𝒕𝒉𝒊𝒏𝒈 𝒃𝒂𝒅 𝒆𝒗𝒆𝒓 𝒉𝒂𝒑𝒑𝒆𝒏 𝒕𝒐 𝒚𝒐𝒖?”

Get ready for a laugh-out-loud, adrenaline-charged adventure in Untamed Aggression.

This series is something special, and I hope we'll see much more of these guys in the future!

𝑴𝒂𝒓𝒄𝒖𝒔 𝒘𝒐𝒖𝒍𝒅 𝒂𝒍𝒘𝒂𝒚𝒔 𝒃𝒆 𝒉𝒊𝒔 𝒑𝒓𝒐𝒕𝒆𝒄𝒕𝒐𝒓, 𝒃𝒖𝒕 𝒉𝒆 𝒘𝒂𝒔 𝒂𝒍𝒔𝒐 𝒔𝒐 𝒎𝒖𝒄𝒉 𝒎𝒐𝒓𝒆. 𝑯𝒆 𝒘𝒂𝒔 𝒉𝒊𝒔 𝒍𝒐𝒗𝒆, 𝒉𝒊𝒔 𝒃𝒆𝒔𝒕 𝒇𝒓𝒊𝒆𝒏𝒅, 𝒕𝒉𝒆 𝒎𝒂𝒏 𝒉𝒆 𝒕𝒖𝒓𝒏𝒆𝒅 𝒕𝒐 𝒘𝒉𝒆𝒏 𝒉𝒆 𝒘𝒂𝒔 𝒇𝒆𝒆𝒍𝒊𝒏𝒈 𝒔𝒄𝒂𝒓𝒆𝒅 𝒐𝒓 𝒍𝒐𝒏𝒆𝒍𝒚. 𝑯𝒆 𝒘𝒂𝒔 𝒂 𝒈𝒊𝒂𝒏𝒕, 𝒔𝒄𝒂𝒓𝒚 𝒃𝒊𝒌𝒆𝒓 𝒘𝒊𝒕𝒉 𝒂 𝒉𝒊𝒅𝒅𝒆𝒏 𝒉𝒆𝒂𝒓𝒕 𝒐𝒇 𝒈𝒐𝒍𝒅. 𝑻𝒉𝒆 𝒍𝒐𝒗𝒆 𝒕𝒉𝒂𝒕 𝑴𝒂𝒓𝒄𝒖𝒔 𝒉𝒂𝒅 𝒇𝒐𝒓 𝒉𝒊𝒎 𝒂𝒏𝒅 𝒉𝒊𝒔 𝒄𝒓𝒆𝒘 𝒘𝒂𝒔 𝒐𝒏𝒆 𝒐𝒇 𝒕𝒉𝒆 𝒓𝒆𝒂𝒔𝒐𝒏𝒔 𝒕𝒉𝒂𝒕 𝑮𝒂𝒗𝒊𝒏 𝒉𝒂𝒅 𝒇𝒂𝒍𝒍𝒆𝒏 𝒔𝒐 𝒉𝒂𝒓𝒅 𝒔𝒐 𝒒𝒖𝒊𝒄𝒌𝒍𝒚. 𝑲𝒊𝒏𝒅𝒏𝒆𝒔𝒔 𝒂𝒏𝒅 𝒍𝒐𝒗𝒆 𝒍𝒊𝒌𝒆 𝒕𝒉𝒂𝒕 𝒘𝒆𝒓𝒆 𝒓𝒂𝒓𝒆 𝒊𝒏 𝒕𝒉𝒊𝒔 𝒘𝒐𝒓𝒍𝒅.

[Dee Layton · Rating 5 out of 5]

First orders I want to say thank you so much for the opportunity to advance read this book I am hooked on this series like nobody would ever believe.
I have become a huge Shadow viper follower if you must say. Matthew Dante is one heck of a writer because I'm telling you what I cannot wait for book 5. Now this is book four in the bikers of mayhem series.
This amazing book is about Marcus the leader of the Shadow vipers and sweet little low Gavin. To take the words right out of Gavin's mouth, "My taste in men can't be trusted," and boy is that true.
So Gavin is a hopeless romantic and just the sweetest but he swiped right on the wrong one. He swiped right on the Valentine killer. Just when he thought he was going to be done for her that's when Marcus stepped in and saved him. And from that point on the book just gets more and more amazing. I thought the character development for this book was absolutely phenomenal. The romance was absolutely phenomenal. The whole opposites attract was just absolutely amazing, as well as the age Gap. Marcus was 39 Gavin was 24 so Gavin just was hopelessly in love with Marcus after he saved him.
Overall, this was the greatest book untamed aggression was just it for me. Now I will say all four of the bikers of mayhem books out currently is absolutely fantastic. Matthew Dante is a phenomenal author and when he thought of the series it was top tier.

[Reed · Rating 5 out of 5]

I have enjoyed all the books in this series but this one just gave me the can’t set it aside reading.

Marcus has had his share of issues from the time he was a young kid but always being the parent seems to be his way of life. It sure directs his life being head of the Shadow Vipers bike club. When he is asked by the sheriff to protect Gavin he is thrown out of his comfort zone. Marcus gave me more than one lol moment.

Gavin, looking for more than the no attached lifestyle, goes on a date with who he believes is a doctor. This date does not turn out at all what he expects. He ends up needing protection from a serial killer and finds himself faced with a biker who doesn’t know what to do with him. Gavin from the beginning is mouthy, flirty and a general disruption to Marcus’s life.

To me this is a fun, comfortable romance. I started it and found it easy to read and hard to put down. I can’t wait to see the next book in the series.

[Marharyta · Rating 5 out of 5]

💕 I know you’ve all been waiting for Marcus’ story. The leader of the Shadow Vipers. The protector. The brains behind the operation. The father figure. But let me tell you first about Gavin.

No one writes a sassy, smart-mouthed hopeless romantic like Matthew Dante. And Gavin is all that and more. He's independent and confident, but he just wants someone to love him. He's popular and charismatic, but as an influencer, all those relationships are superficial. When he finds himself in need of protection, he finds not only the beast that is Marcus, but best friends and found family.

Now, we've watched Marcus at the side lines for the last 3 books. His closest friends and even his little brother have found long lasting love. But as their leader and protector, Marcus, at thirty-nine, does not believe a relationship is in the cards for him. His focus would be on the Shadow Vipers, the business, and in keeping his family safe.

His family. His found family that is, and his step brother Ace. Because his parents could never be counted on. And that's something Gavin knows all too well. I love how they both still have parents, but parents don't always mean family. The whole gang is back, and I couldn't love Ace and Lucas more for how they embrace Gavin into their fold. Gavin, who by the way, shares a lot of similar personality traits with Ace. And although protecting people is in his nature, I think it's these similarities that draws Marcus to be so fiercely protective of Gavin.

This book is funny and full of fun flirty moments. It is also morally dark, so be prepared for fights, blood, and torture. Be prepared for soft Daddy Marcus and fierce protective Marcus. Be prepared for the trio of Ace, Lucas, and Gavin. Be prepared for found family and a group of bikers who will rally behind their leader without question and embrace the newest member of their family.

ARC Read 23Apr2026

[Kai · Rating 1 out of 5]

I have to say, I want into this having high hopes but sadly fell flat. I was not onboard for this story. I found it boring to be honest. First I found Gavin to be completely annoying and acts more like a kid than an adult, he was very unlikable. Marcus I did find somewhat interesting and likeable, but the pairing just did not work for me. There was no growth or chemistry between the characters. I really wish this could have been better and OMG I hated the whole influencer by day and romantic with bad taste in men joke just was played out. The instant love was very over done. The action was good for the most part. I just hate that is felt more like a teenage brat than a adult for Gavin.

[Yvonne · Rating 5 out of 5]

The fourth book in one of my favorite series, and it certainly did not disappoint me.

Just like in the previous books, there were lovable characters, humor, and suspense.
It was a delightful story to read; the characters took a piece of my heart.

💞Thank you to the Author for the opportunity to read and review this ARC💖

[Lyndsay TC · Rating 4 out of 5]

The head of the Shadow Vipers, Marcus got unexpectedly waylaid by social media influencer Gavin while protecting him from a serial killer. Marcus never thought he would fall for anyone much less a man but the heart knows no bounds and his heart wanted Gavin whether Marcus liked it or not. Action, found family, shenanigans, spice and love make up this fun book.

[Michael T · Rating 4 out of 5]

Marcus is the leader of the Shadow of Vipers, a biker gang. Gavin is put under his protection from a vicious attack by a serial killer. Forced proximity, charisma, angst, spice and comedy make this one another must read by Matthew Dante!

[Bear_reads_romance · Rating 4 out of 5]

Absolutely loved Marcus and Gavin! Marcus is such a protector and there's no one better to protect Gavin. I live that it just happen naturally with them and I love this group.

[Natalie · Rating 4 out of 5]

I really enjoyed Marcus’ story. Lots of spicy, lots of bikers doing crazy stuff, and a cute puppy.

[Tania · Rating 4 out of 5]

3.5 rounded up to 4 stars
I liked Gavin’s sassiness but overall I didn’t feel the story lived up to the potential.
Didn’t really buy into the GfY from Marcus

[Marion Dayen · Rating 2 out of 5]

l’idée est bien c’était grave ma came mais l’écriture c’est catastrophique c’est gênant