Title: I Am My Brother's Keeper

Pairing: Gabriel/Lucifer (Lubriel)

Rating: R

Summary: Lucifer's first heat comes as a surprise for everyone

Warnings: slash, angelcest, alpha/omega dynamics, bottom!Lucifer, top!Gabriel, Omega!Lucifer, Alpha!Gabriel, marking, claiming, knotting, pre-fall, first time, first heat

A/N: For the Gabriel to my Lucifer, she's been waiting a while for this fic and I'm happy to say that I finally finished it :) There will be a sequel, cuz my brain already planned out the next part before I could finish this so be on the look out

This was meant to be a short fic, and it quickly spiraled out of control XD I blame RPs with Hyper Kid :P

Lucifer's first heat comes as a surprise for everyone, for one, they'd all assumed that he was an alpha like his brother before him. However, as it turned out, that was not the case. No, the Morningstar was in fact an omega.

When his first heat hit, he should have been with Michael, a known alpha, to help him through his heat. He wasn't. He could have even been with Raphael, who though he was a beta, was still equipped to help Lucifer. He wasn't with Raph either.

No, when his first heat hit, Lucifer was in the gardens with Gabriel. Like everyone assumed Lucifer was an alpha, they'd all just assumed that Gabriel was an omega. There'd been no outward signs from the messenger angel to signify that he was an alpha, of course there hadn't been any signs pointing to Lucifer being an omega either.

They're in the gardens when Lucifer starts to feel warm. Which in itself is odd, he's usually so cold, and yet, right now it feels as if there's a fire burning inside of him.

He tries to shake it off, maybe Dad's just having fun playing with the temperature. For the most part he succeeds in ignoring his gradually increasing temperature. That is until he notices the fingers of his right hand are trembling ever so slightly.

He clenches his hand into a fist at his side to try and force away the trembling. It doesn't work.

The only reason he actually manages to ignore the temperature is because his skin feels as if it's suddenly crawling. Well not crawling, but he feels as though he has an itch, but he can't quite scratch it or pinpoint where the itch is coming from.

Tugging at the collar of his shirt he bites his bottom lip feeling a fine sheen of sweat break out across his forehead. He has no clue what's happening, but it feels as if he's burning up from the inside out.

"Gabe…" his voice comes out scratchy and worn and not at all like he's used to. Clearing his throat he tries again, "is it just me or is…" he trails off when he catches sight of Gabriel.

The archangel's normally golden rimmed eyes are now dark with lust as they fixate on Lucifer, his breathing coming out a little harsher as his tongue pokes out between his lips to swipe over his bottom one.

Lucifer swallows looking back at Gabriel. He's seen that look before; from Michael. The look that screams "I'm an alpha and I sense an omega in heat", and if that's the case and Gabriel's an alpha, then that means…

Lucifer doesn't have time to focus on that epiphany because he's now doubled over groaning. His skin feels hot to the touch, but there's an internal burning too. Looking up at Gabriel he starts to shake a bit, he can feel himself start to sweat as he tries to focus on his next words.

"Gabe…I…I need-"

Swallowing Gabriel keeps his distance, "I'll get Michael…"

Lucifer shakes his head, he doesn't think he can wait that long. "No," he pleads, voice cracking as he looks up at Gabriel from where he's still doubled over, nails digging into his thigh.

Gabriel looks uncertain biting his bottom lip as he asks "are…are you sure?"

Nodding frantically Lucifer forces himself to stand up straight to look at Gabriel, "please Gabriel, I need this," he pants out licking his lips as he stares at his brother a little desperately.

That seems to do the trick.

Gabriel is on Lucifer in seconds, a hand fisting his brother's hair as he pulls him closer mashing their lips together. Moaning, Lucifer grasps at Gabriel's shirt, his hips grinding forward trying to seek out extra friction. Nipping at Lucifer's bottom lip, Gabriel moves his hands to grip Lucifer's hips as he grinds back against him.

Thumbs brushing over Lucifer's hip bones, Gabriel kisses down his neck.

"Clothes off, now," he growls out against Lucifer's collarbone.

Nodding Lucifer starts to tug at his pants; his hands are shaking as he shimmies out of his clothes. He's so eager for this, wants it so bad, he can't seem to get out of his garments fast enough.

Eyes roaming over Lucifer's body, Gabriel snaps off his own clothes. He hasn't got nearly enough patience to deal with taking the garments off by hand. No sooner has Lucifer's shirt fallen to the wayside, is Gabriel moving in close again, hands resting on Lucifer's hips, he kisses him on the mouth, taking Lucifer's bottom lip between his teeth sucking gently as he back him off the main trail to a nice alcove to the east of the Tree of Knowledge.

Laying Lucifer down on the grassy field, Gabriel settles in the space provided by his brother spreading his legs, ghosting his fingers up Lucifer's chest to rest on strong shoulders as he ducks his head down to resume their kiss.

Moaning softly into the kiss Lucifer's eyelashes flutter as he looks up at Gabriel, pupils blown wide with want, "Gabe, please…I need-"

"Shh, I'm gonna take good care of you," Gabriel murmurs running a hand up the inside of Lucifer's thigh.

Breath hitching, Lucifer nods, his thighs trembling as Gabriel trails his hand up, fingers pressing against Lucifer's dripping hole. Biting his bottom lip, Lucifer looks up at Gabriel with a pleading look, "I need… I need…"

"I know what you need Lu," Gabriel murmurs teasing Lucifer's hole, "and I'm gonna give it to you."

Lucifer may be wet and begging for it, and Gabriel may be harder than a rock, but he's fighting every alpha instinct screaming at him to flip Lucifer over onto his hands and knees and just bury himself to the hilt in his older brother and fuck him senseless, because this isn't just Lucifer's first heat, this is his first time, and Gabriel wants it to be special.

Slipping a finger into Lucifer, Gabriel brushes the fingers of his free hand across Lucifer's abdomen, slowly moving up his brother's body, "absolutely perfect Luce."

Whining Lucifer grinds down against the intruding finger. He wants more, needs more; now.

Gabriel however, has other plans. He's working slow, leisurely thrusting his finger in before he adds a second finger. Lucifer is beyond ready, he's dripping wet as he rocks back against Gabriel's fingers moaning softly, legs spread wide.

A needy moan passes through Lucifer's lips as he looks up at Gabriel, "Gabriel…please…"

"So beautiful like this Luce," Gabriel murmurs crooking his fingers. "All wet for me, want me to fill you up baby? Want my knot don't you Lu," he asks brushing his fingers over Lucifer's prostate.

Gasping, Lucifer arches up off the ground nodding as he all but sobs out in need "Yes, want you Gabe…please, need it so bad, need you," he babbles.

"Shh, I've got you Luce," he says softly as he removes his fingers and moves to press the head of his cock against Lucifer's slick hole.

Eyes clenched, Lucifer's fingers dig into the soil beneath him as he lets out a breathy moan trying to grind back against Gabriel. He needs to be filled, his whole body is screaming for it, and Gabriel is so close it almost hurts with how much he wants it.

Gabriel picks up on Lucifer's desperation, hands moving to Lucifer's hips he slowly pushes into him. His breath hitches as he bottoms out, fully sheathed inside Lucifer. Even with all the prep and natural lubricant, Lucifer is still oh so tight, and Gabriel can't help the moan that falls past his lips at how perfect Lucifer feels around him.

Leaning forward, he hooks Lucifer's legs over his shoulders as he presses open mouthed kisses along Lucifer's neck, "gonna make you feel good," he murmurs as his thumbs brush over Lucifer's hipbones, starting to rock his own hips.

He keeps his movements slow, licking along Lucifer's neck as he rocks his hips, snaking a hand between them to wrap his fingers around Lucifer, stroking him in time with each thrust.

Gasping Lucifer arches up into Gabriel's touch, the slow burn of being stretched feels good, it's like a small reprieve from the constant cry of 'fuck me' that his body seems to be shouting right now.

Stroking Lucifer, Gabriel sucks a mark at the base of his brother's neck, "so perfect," he murmurs against warm flesh as he rocks his hips forward.

"Gabriel…"

Tilting his head up to look at Lucifer, Gabriel moves his free hand to cup Lucifer's cheek, his thumb brushing along Lucifer's bottom lip. "What is it Lu?"

"Fuck me," he murmurs breathlessly, "need it bad Gabe…"

With Lucifer's blessing, it's as if a switch has been flipped in Gabriel's mind. His teasing slow pace of thrusting picks up, as he runs his thumb over the head of Lucifer's cock. His hips slam forward, thrusting into Lucifer, shifting to angle each thrust in against the Morningstar's prostate.

Lucifer's eyes slip shut in pleasure as he tilts his head back letting out a low moan. He's grinding back against Gabe eagerly as his fingers claw at the ground, blades of grass being ripped from where his fingers have clenched around them.

Gabriel's moans are muffled from where he's got his mouth against Lucifer's neck. Thrusting into his older brother, Gabriel strokes Lucifer, using the Morningstar's precum to ease the slide of his hand over Lucifer's cock. Biting at Lucifer's neck, Gabriel marks him, sucking angry red marks up and down Lucifer's neck as he hammers against his prostate.

Practically sobbing in relief as pleasure shoots throughout his body, Lucifer runs his hands down Gabriel's back; nails scratching along Gabriel's shoulder blades. Arching his back Gabriel lets out a low moan as he thrusts into Lucifer.

"Fuck, Lu…you don't know what you do to me," he murmurs, voice rough and worn.

Eyes clenched shut; Lucifer tilts his head back squeezing around Gabriel, feeling his orgasm start to build at the base of his spine. Warmth pooling in the pit of his stomach, Lucifer moans loudly clutching at Gabriel.

Breaths coming out in harsh pants, Gabriel ducks his head nuzzling Lucifer's neck as he feels his knot start to swell. Lucifer's already tight around him, but as his knot swells, Gabriel can feel Lucifer stretch even more around him, his hole greedily taking him in all the way.

Lucifer arches up crying out in ecstasy. He feel so full, like he's being split in half, but it's such a good burn and for once his mind feel clear, haze of his heat dulled by the feel of Gabriel laying claim to him.

Biting at Lucifer's neck, Gabriel winds his fingers around his brother's cock and with a few expert strokes brings Lucifer to his first orgasm.

Eyes wide, Lucifer tilts his head back a garbled whine falling past his lips as he cums across his stomach and Gabriel's hand. He feels as though he's been electrocuted, nerves frayed as pleasure rolls through him, hips jerking up as he clenches around Gabriel.

The feel of Lucifer clenching around him set Gabriel off, hips jerking forward thrusting deeper into his brother as he cums hard. Crying out Lucifer's name as he cums, Gabriel slumps forward, utterly spent, draping his body over his brother's lax form.

They stay that way, Gabriel pressing soft kisses over the marks marring Lucifer's pale flesh as Lucifer runs his hand soothingly over the scrapes down Gabriel's back, while Gabriel's knotted in Lucifer.

The haze of the heat falling away Lucifer tilts his head to face Gabriel kissing him soundly.

This time when they kiss, there's no urgency of hormones pushing the matter, it's just them and it feels right. Lucifer hums softly holding Gabriel close to him. Even after Gabriel's knot dissipates, they stay there in the garden entwined with one another trading lazy kisses.

"Thank you," Lucifer murmurs, fingers playing with the hair at the nape of Gabriel's neck.

Gabriel just shakes his head nuzzling against Lucifer, "I told you I was going to take care of you Lu."

Smiling softly up at Gabriel, Lucifer leans up to kiss him, glad his heat hit when it did.