(Y/n) took notice of how close William and Sherlock were before the fall, but even more so when they returned after three years.
To the surprise of the Morigroup William confessed to (Y/n) being his lover and his wishes for her and their relationship to remain out of the public eye.
When Sherlock entered the picture she realized she couldn't give William what he could.
So she allowed them to have their moments.
Over the course of their time together their bond grew stronger.
(Y/n) began to feel a bit jealous but it didn't overshadow her love for the blonde.
If anything it strengthened it.
When she watched the two plunge into the Thames her heart sunk and she feared she lost William for good.
Upon seeing the two men her heart skipped a beat and she immediately ran into her lover's arms.
William was startled but hugged back.
Sherlock rubbed the back of his neck.
(Y/n) pulls away and notices how much they had changed.
It also didn't go unnoticed how close their hands were.
(Y/n)'s heart sank once again.
"I see." She whispers and turns away.
William notices what she meant and frowns. "It's not what you think."
"William don't lie to me." She whispers then looks at Sherlock.
The said man looks away, unable to say anything or look her in the eye.
Later that night William walks into their bedroom and sees (Y/n) sitting in her rocking chair in the corner.
Sherlock sits on the bed but stays quiet.
The woman looks from the detective to the professor. "I knew there was more than friendship but I stayed quiet. I knew he could give you what I couldn't, intellectually. I didn't ever imagine it was intimately as well. I apologize if I was inadequate as a lover."
"(N/n) please don't belittle yourself. You were a beautiful lover. I still love you."
(Y/n) stops rocking and looks confused. "Then what-"
"I want you both."
Her eyes widen and cheeks darken.
"I know it's selfish and you have every right to decline."
"It was my idea to ask if you were ok with it." Sherlock finally speaks. "He was yours first and you have final say."
"Wait, what if I said I wanted him for myself? Would you leave and William would you accept that?"
The blonde frowns but nods.
Sherlock crosses his arms but nods as well.
Although it was a tempting idea, she knew it was more selfish to keep William for herself than him asking if Sherlock could join.
If he wanted the detective too then she would have to get used to him.
Her blush gets darker as she thinks about the action itself.
"How would we..." She trails off, unable to bring herself to say it.
"Liam would be in the middle. I'm sorry but neither you or I would get satisfaction from each other."
"Oh. I understand." She mumbles quietly.
"If you would be up for it we could try it out now." Sherlock offers and looks between the two. "Everyone left for the night."
William looks at (Y/n).
"I suppose we could." She responds after a bit of debating.
Holmes loosens his tie and takes off his jacket. "I'll let you two have some fun before I join. It's been three years after all."
William smiles at Sherlock then (Y/n).
The woman stands but looks at Sherlock. "If you have no interest in women Mr. Holmes how will you take pleasure in us?"
"Liam is all I need."
William blushes slightly while he undresses. "Sherly." He mumbles, embarrassed.
The blue haired man smirks at his friend.
(Y/n) takes off her robe then her nightdress.
William looks her over and remembers how much he enjoys her body. "As breathtaking as I remember."
"You as well." She compliments, looking him up and down.
"Get comfortable darling."
(Y/n) does as told, laying on the bed and spreads her legs.
Sherlock moves to the rocking chair and strokes himself slowly.
William lays between her legs and immediately dives right in.
Her moans echo in his ears, spurring him on.
His tongue, teeth and fingers pleasure her.
William moans against her, making her whimper.
Due to it being such a long time since she's done anything sexual it doesn't take long for her to release.
Sherlock smirks and walks over. "If you think it's attractive when he's between your legs, imagine how he looks when I'm between his."
(Y/n) could barely register what the detective said before he begins pleasuring William.
Immediately the blonde whimpers and moans weakly.
He moves to his hands and knees, although they're a bit shaky.
(Y/n) watches William's expression change and was surprised how much she liked it.
Never did she think she could enjoy watching her lover be had by someone else.
Sherlock lubes up his fingers before dipping in at the same time he takes William's length into his mouth.
William grips the sheets and when he makes eye contact with the woman under him they both blush more.
Due to the double stimulation William doesn't last very long either.
When William comes down from his high Sherlock moves to kneel behind William.
(Y/n) looks at the position and bites her lip. "Darling," she whispers. "How long have you been hiding this side of you?"
The genius couldn't think of an answer so instead he kisses her.
(Y/n) kisses back but gasps when he thrusts into her.
This allows his tongue to explore and tangle with hers.
Sherlock waits until William is ready to slide in himself.
The blonde whimpers at the feeling.
The detective leans his chest against William's back then blows on his ear.
(Y/n) grips the sheets and tries holding her legs in place.
William uses her legs to stabilize himself while he and Sherlock thrust.
His body isn't used to the double stimulation so his mind begins to go blank.
(Y/n) tugs on his hair weakly as his head falls onto her chest.
His head turns and he begins sucking on her breast, taking her nipple between his teeth.
Sherlock holds William's hip with one hand and rubs his back with the other. He grabs William's nape, gently brushing fingers with (Y/n).
With each thrust they got closer and closer.
William is the first to release, although (Y/n) follows close behind.
Sherlock pulls out and uses a tissue to finish.
The couple pants heavily as they lay on the bed, curled into one another.
The third wheel feeling comes back to Sherlock seeing William and (Y/n), but he pushes that aside.
"Lock come join us." The woman whispers softly.
William laughs softly at the nickname.
The detective rolls his eyes but lays on William's other side.
The three lay comfortably together, using only the light bedsheet for coverage before falling asleep.
