Title: Once In A Lifetime

Author: gabe1990

Prompt(s) Used: Prompt #48.

Pairing/Characters: Arthur/Merlin/Gwaine. Merlin/Arthur. Gwaine/Merlin. Gwaine/Arthur. Gwaine/Leon (at ending).

Rating: Mature/NC-17

Word Count: 1,004 for his chapter.

Summary: Gwaine has always been in love with his best mate, Merlin. When Merlin and Arthur, Merlin's partner of five years, proposition him to help spice up their love life, how can he possibly refuse? But after one night, could he ever consider giving them up?

Warnings/Content Notes: M/M/M - Threesome sex. Explicit sexual content.

Author's Notes: Written for prompt #48 of Gwaine's Quest on LiveJournal.

Disclaimer: The characters depicted belong to Shine and the BBC. No profit is being made.


Chapter One

When Gwaine was invited over to his best mates flat that he shared with his partner of five years, he could honest say he did not know why. He had never been invited over before. He was more of a spontaneous kind of person that always seemed to come to early – or late, depending on the time of the week. Of course, he had a few ideas; things like his assistance was needed to fix some electrical appliance that Merlin had broken, as both the men were completely hopeless with the wonders of technology.

The true reason was somewhere in the far reaches of his mind. After all, not everyone gets invited to their friend's place and assumes they are going to be asked to join them in the erotic sex fantasy that would be a threesome.

Well, at least he did not.

Gwaine choked on his drink.

Merlin reached over to pat his friend on the back, concerned. "Are you okay?"

"You-you…what?"

"We, as in Merlin and I, want you to have sex with us both…" Arthur repeated, this time much slower as if talking to a small child.

"Wha-how-what?"

"I'm sure I don't have to explain the mechanics of sex to you of all people." Arthur smirked, amused.

Gwaine gave him a dry look and Merlin elbowed him sharply in the ribcage.

"Of course not, just ask your father," He bit back, causing Arthur to frown darkly and Merlin to give him 'the look' – the one of disappointment. He sighed, running a hand through his wavy hair. "I did hear you the first time…but why? Why me, of all people? I'm your friend…"

And I'm in love with you – this is just my luck…

"We've spoken about this – quite a lot actually – and it's something we both want to do. You of all people should know that that has been my, ah, kink for a while now," Merlin explained awkwardly, his cheeks flushed pink at the conversation. If Gwaine was not so gobsmacked, he was sure he would have enjoyed the pleasant colouring of his face a lot more. All he could do was nod, absentmindedly.

"I want the, ah, third person to be someone I can trust and I care about, that would be willing to join us. Sex isn't just about the primitive need anymore, I want emotion in it…and you were the only person I could think of. Plus, um…" he trailed off, his face reddening.

"Plus, you are incredibly gorgeous and someone that has played a pretty important role in many fantasies on occasion," Arthur finished, a small smirk on his face as he gauged the other man's reaction.

Gwaine had to admit, at least to himself, that the offer was not entirely off putting. In fact, he was pleasantly flattered at the announcement. It was not everyday that two very attractive and willing men confess that he was a source of their wet dreams. But did that really mean he wanted to participate?

It was sad to say, but yes, he was very enthusiastic to help them make a very sticky sandwich. He had known since Year nine of Secondary School that he was in love with the lithe, blue eyed man that was Merlin Emrys. He had never acted on it though, their friendship meant too much to him, and when he had started a relationship with Arthur in their last year, he had gracefully stepped back to allow his best mate to be happy.

Now five years later, he was being offered the chance to have sex with the man he still had feelings for. This was never going to happen again. He'd be stupid to allow the opportunity to pass him by so easily.

And it wasn't as if Arthur Pendragon was not a sight to behold. He was still as gorgeous as Merlin, even with their completely opposite looks, with his wavy blond hair and chocolate brown eyes. He could easily imagine the two together, attached by the mouth and crotch, would become every girl's (and some guy's) fantasies.

Without meaning to, he could see the two bodies, one tanned and the other pale, rocking against each other in a frenzied pattern, engorged and slick cock's sliding against each other. He could hear the husky whispers of approval, encouraging more movement, more friction. He could see their swollen lips, sore from their insistent, arousal ridden kisses, and the indent of nails in Arthur's strong back as Merlin held on for dear life.

Gwaine swallowed heavily at the thought.

"Of course you don't have to say yes," Merlin quickly assured, "We're not going to force you into anything you don't want to do. It's entirely your choice but could you; um…could you just think about it?"

When those pleading eyes were turned to him, he had no choice but to obey. He sighed loudly, mentally cursing himself for being so whipped by a guy that is not even his partner; would never be.

"Of course Merlin. I'll think about it…" he agreed reluctantly.

"Take all the time that you need," Merlin replied, quickly, a grin breaking out on his face, "I don't want you to rush in, undecided, and find you've made a mistake. I want to make sure you're okay with all of this…"

"Merlin, he's already agreed to think about it," Arthur interrupted, resting his hand on his partner's shoulder, "You don't want to overload his system before he's even made a decision, do you?"

Merlin looked sheepish, flushing pink and biting his bottom lip. Instantly, Gwaine's eyes zeroed in on the bitten flesh, looking so red and plump and just damn irresistible. Vaguely, he reminded himself he could have the chance to kiss that Cupid's bow. His heart beat increased at the thought and he did not have enough rational thinking to force it to calm. He blinked once, forcing himself out of his state, and glanced at Arthur quickly, silently wondering whether he had been caught.

Arthur just smirked knowingly.