The title and inspiration for this little fic come from the song In My Veins by Andrew Belle. It's very Four and Tris, and I highly recommend you give it listen before reading!

I don't own Divergent (but Four is my literary boyfriend). Words in italics belong to Veronica Roth and her brilliant mind.

"Tobias closes his eyes. I trust the dwindling fire to disguise us as I run my hand up his back, touching each tattoo without seeing it. I imagine Erudite's staring eye, Candor's unbalanced scales, Abnegation's clasped hands, and the Dauntless flames. With my other hand I find the patch of fire tattooed over his rib cage. I feel his heavy breaths against my cheek.

"I wish we were alone," he says.

"I almost always wish that," I say."

Soon after Tris' fingers stop outlining the ink covering my skin, I put my lips to her forehead. She sighs before pulling me to the mat with her. Her breathing quickly evens out, and I can tell she's drifted off. I, however, am not so lucky; despite feeling exhausted to the core, my eyes won't shut and pull the curtain between dreaming and reality down with them.

Instead, I shift closer to her, my hand slipping over her side and resting on the strip of skin exposed between her shirt and pants. My fingers twitch, wanting to follow my gaze as it drifts down the contours of her body that I ache to touch. There are too many thoughts in my head, racing around and jockeying for my attention.

"I would like to discuss something with you..." my father's voice echoes in my mind. There are many things I'd like to discuss with Marcus, but I know that when the time comes, I'll be talking with my fists and not my mouth. My head begins to pound as my thoughts move to Evelyn. I don't know whether or not to trust her, and I yearn for the Dauntless compound and the anonymity my numerical nickname provided. No "Eaton" attached to Tobias influencing things there. I'm surprised by the longing to be back in the Pit when I was so eager to get out only a short time ago. But of course Tris changed that. Tris changed everything. Even now, above all the other noise in my head, there she is.

Just the sound of her voice can pull me back, like it did that night in the control room. Even though she's right beside me, her flat stomach rising and falling beneath my hand, suddenly it's not enough. A desperate need bubbles up, her presence filling my veins, and my grip on her waist tightens. She stirs, and I realise that the space we're in is too crowded; the breaths and murmurs of the factionless press down, suffocating me. All I know is that what before was a wish has evolved into something more. We needto be alone. Now.

"Tris," I whisper in her ear, "wake up." She rouses and rolls over to face me, her eyes popping open.

"Waswrong?" she slurs, her voice thick with sleep.

"Nothing, nothing," I reassure her. At least nothing beyond the normal. I don't want to revisit the problems morning will bring again, so instead I sit up and lace my fingers together with hers. There are too many people here. "Let's go for a walk."

She follows a half-step behind me, one hand gripping mine and the other rubbing the sleep out of her eyes. We weave between the mats on the floor, moving across the room until we reach the hall lined with metal doors. One near the end is ajar, and Tris raises her eyebrows, the corner of her mouth lifting in a smile as she takes the lead and enters the room. I shut the door as quietly as possible, sealing us into a space that, at least for these precious moments, is ours.

Muted light filters into the room through the dirty windows. It's that time of night where secrets can more easily be shared and words somehow carry a greater significance. I stare at Tris, and she meets my gaze levelly, as she always does - unlike others who can't seem to handle what they see in my eyes. "I love you. I - " trailing off and clearing my throat, I step toward her. We're close enough that our fingertips brush against each other. "I want you, Tris. I need you." I press up against her and her eyes widen. I know that she's blushing; she tries to conceal it, but she can't hide from me. "This feels right, doesn't it?"

She pauses, and for a second I think maybe I should have just let her sleep. But then she cups my cheek, bringing her thumb to my lips and ghosting over where her mouth is a moment later. "I trust you," she murmurs, all at once permission and a privilege. I hope that this heady desire, moving like a drug through my blood, is filling her up, too. She fists my shirt in her hand, tugging me even closer, then pushes it up and over my head so it falls to the floor. I take that as all the confirmation I need. There's no hesitation after that. My hands glide to the curve of her ass, squeezing lightly before lifting her up. She wraps her legs around me as I walk us backwards to the table in the corner of the room.

The table legs scrape the floor in a harsh serenade as I set Tris down and move between her thighs. Her hair falls around her face, and I push it back before fisting it tightly in my hands. I slowly breathe out and lean my face down to hers, bringing our lips together. She moans in response as our tongues tangle.

My hands travel down to rest on her hips, my thumbs sliding along the taut skin of her stomach behind the waistband of her pants and skimming the edge of her underwear. She arches her hips up, giving me the opportunity to slide her clothes off, so her bottom half is now bare before me. I run my hands over her thighs, the soft skin like silk under my rough hands.

She looks up at me, her eyes slightly haunting in the dim light. Blinking slowly, she lifts the hem of her shirt and pulls it off in one quick movement. The tension in the room is almost unbearable, and my pants feel about two sizes too small. My eyes move to her chest as my hand moves behind her back, undoing the clasp of her bra. It falls to her lap and my gaze quickly flicks back up to her face. A light laugh falls from her lips, and she places her hand over my heart and says "There's not a look-but-don't-touch rule with us. I'm yours, Tobias."

A low groan works its way up from deep within my chest and forms her name as it escapes my mouth. My heart skips a beat, and I want to know if hers is beating as fast as mine. It is. The same staccato rhythm. I move my hands to her breasts and revel in their softness. She pushes her hips toward mine, and I realise that I'm still wearing my fucking pants, which is stupid. I stumble slightly as I push them off, and smile when she wastes no time shoving my boxers down to join them.

She lowers herself across the table, and I quickly follow to hover above her. Her hand reaches up and runs through my hair. Down my back. Nails scratching skin. I love that she's leaving her mark on me. Soon I'll get a tattoo that represents her; I will wear the honour of her permanent and profound role in my life. I dip my head and kiss her breasts, gently sucking each of her nipples, feeling goosebumps rise on her skin. The sounds she's making spur me on. She bites my bottom lip as she kisses me, almost unravelling me before we begin.

We line up so our bodies are ready to connect, her magnetism preventing me from allowing any distance between us. I move forward slowly, watching her face intently.

She scrunches her nose and I stop, my arms shaking with the effort it's taking to control my actions. Her mouth shapes itself into a perfect O and she lets out a shaky breath. "It's okay," she half laughs, "this feels...good. The first time is always the hardest, right?" Her words bring me back to before her first fear simulation when I told her to be brave. That feels like a million years ago now, but a part of me is always wanting to protect her. Of course she doesn't need that, and I respect her for it. This moment we're in now, though, is something that acutely requires my attention. "Just tell me if I need to stop," I say, and she nods.

I move my head down and nip her earlobe, a shiver of pleasure rippling through me and passing to her. Urgency consumes me once again, and I move my hips, slowly at first, then building in intensity. We move together, and the sound of her moaning deliciously fills the space around us. This tight, hot ball of tension seems to expand out from my core through my limbs, and Tris's breath, heavy on my cheek, feels amplified. Everything is heightened, and just when it feels like I can't go any higher, I feel her tightening around me. An indescribable euphoria pulses through my body, whiting out my vision as I scream her name. I feel as if I've been rocketed to somewhere far beyond these walls, but her breathless voice echoing my name brings me back.

Even with all the times I've felt like there wasn't an inch of space left between us, nothing compares to this. I savour a feeling of wholeness never experienced before.

I roll onto the table beside Tris, and her head lolls to look at me.

"Oh, my God," she breathes. She traces a line down my chest and it makes me shiver, so I pull her to me.

"How do you feel?" I ask her, my voice gritty. "I don't think I remember how to form coherent thoughts," she responds, "but that was...something else. Nothing like I imagined it would be. So much more." She squeezes my side and my eyes drift shut. I reluctantly open them and sit up slightly, leaning on one elbow so I'm looking down into her eyes. She smiles languidly back and suddenly I'm exhausted in the best possible way. No amount of running or jumping off of trains has ever made my heart pound like it just did.

My focus shifts to the birds in flight across her collarbone; she embraced that fear, and my heart clenches because it's clear we've conquered what was once another. I kiss each bird, just like that time on the train. It was an intense moment at the time, but everything has shifted now. I'm tethered to her, feeling the pull like it's a physical thing between us. I taste the salty sweetness of her skin again and again. If it's the only thing I taste for the rest of my life, that will be more than okay. We're connected in every way now. Nobody can take that away from us.

We're Four and Six. That's all that matters.

This is my first foray into fic and I'd love to hear your feedback! There are not enough words to say thank you to the people who read this over and helped me make it better, and then encouraged me to post. And Flooz, thanks for asking that initial question. xx