Author's Notes: First and foremost, while I don't consider this to spoil anything, others who have not yet watched the entirety of season 6 may wish to tread lightly. Secondly, I'm not entirely sure of some of the details exactly (like when Deb's mother died), so it's kind of a ball-park guess. Also, I don't own Dexter. If I did, things would be a lot different!

There are things Deb doesn't tell her therapist; things that she barely remembers, forgotten dreams and vague inclinations.

"I used to sneak into his room... curl up on his floor. He wouldn't even know I was there."

Except some times, when that wasn't enough. Some times, when she would crawl into his bed, and feel his arms wrap around her.

The first time was when they were children, and the cute little kitten from next door went missing. Deb cried her eyes out, worrying about what might have happened to it, before sneaking into Dexter's room. In his sleep, his eyes flickered but did not open as she slid in beside him. They lay, side-by-side, until he found her in the morning.

"What are you doing in here?" He hadn't yet mastered the art subtlety. His impressions of human interaction were sometimes shaky, at best.

"I'm worried about the kitten." Deb seemed small to him in that instance, her eyes wide and fearful. She missed the flash of expression that passed over his face – his eyes widened momentarily, eye brows shot up. Fear, of being caught, guilt, of hurting Deb. These were things even a child could understand. She sloped out of his room, closing the door behind her. Dexter dashed to his toy box, digging down to the bottom and pulling out a limp blanket-covered lump. He drew the prone, furry figure out. Its ribs moved up and down, almost imperceivable, but definitely moving, definitely alive. Somehow, by some miracle, the little kitten had survived. Dexter eased open his window and lowered the cat to the ground outside. He stashed the blanket back in his toy box and called out.

"Debra! Mom! Dad! Look what I found!"

Debra dashed back in. "What?!" She demanded, before noticing the open window and pushing past him. She ran outside to check the little cat. Dexter, simultaneously satisfied by appeasing his sister and mourning the loss of relief, missed the frown on Harry's face as their Mom took Debra to return the kitten. The cats of the neighbourhood were safe.

The second time was years later, when Deb was hosting her first sleepover.

"He's not really your brother." One girl had sneered. "He's only sort-of your brother. You can even marry him if you want." Her last comment was met with a resounding "eeeewwww" from the girls, hyped up on sugar and an intense game of truth-or-dare. Deb had given the girl an emphatic "he's my brother just as much as Maggie is your sister" and a snub via withheld chocolate. Soon, the other girls forgot the conversation, much more interested, at the tender age of 9, with the pro's and con's of each boy in their grade. But Deb did not forget. Later, when the girls were all asleep (a claim of "Ohmigod you guys, it must be after midnight" forced them to sleep), Deb eased herself out of bed, stepping over the bundle of sleeping bags and spare mattresses, and found her way into Dexter's room. He woke as she was trying to get comfortable under the covers.

"Deb? What's wrong?" He whispered.

"Dex... you're my brother, aren't you?" Her voice was high and vulnerable. Dexter registered the sound. Afraid.

"Of course I am." Harry's lessons were making slight headway.

"Promise?"

"Promise."

She took advantage of the awkward hug Dexter offered to snuggle into his arms, safe from the venomous claims of a venomous girl. Debra woke far earlier than Dexter the next morning, some innate instinct telling her to go back to her room before anyone found them. She was a child. She didn't question why.

The third time, she was 14. Deb was entering an age of awkwardness; new glasses, new school, new body. Her penchant for t-shirts and jeans was a source of great humiliation for Deb, simultaneously making her curves look awkward and disproportionate while highlighting her developing (or lack of) cleavage. 16 year old Dexter was smooth and charismatic, and a little shaky on the duties of an older brother.

In the cafeteria, Deb was taunted by a grade-school friend cum high-school tormentor.

Pointing at Dexter, passing through the hallway, there were taunts of,

"He's so normal and you're just a freak. How could you be related to him? Oh, that's right, you're not."

Debra shied away from the fight.

She found him that afternoon, reading an AP biology textbook.

"Dex." The whine in her voice first attracted his attention. The look on her face kept it.

"What's wrong?" Harry had been drilling him ("You have to look out for your sister now. If she needs help you do everything in your power to do so. Your mother's chemo isn't going so well. I need you to look out for Deb."). Even Dexter, at this point almost completely inept with women, could tell Deb was distressed.

"Why..." She began, "Why don't... How can..." She sighed, in a way that sounded suspiciously like 'fuck'. Her cheeks were flushing. "I need you to take me to the mall." A seemingly innocent request.

"What for?" Dexter enquired. The mall was a longer interruption to his studies than he was willing to offer.

"Just," The flush grew brighter, "girl things."

It was Dexter's turn to feel uncomfortable. "Can't you just go to the market?"

"No!" She moaned. "Not those kinds of girl things. Please can we just go, Dex?"

She'd said 'please', he couldn't deny her.

"Dex," She hissed, "what do you think?"

"I can't tell you if you won't show me." Honestly. A women's dressing room was no place for a teenage boy – sociopath or otherwise. Her answer was to reach around the corner and pull him into the cubicle with her. Gone was the tom-boyish Deb Dexter knew. She now wore a short black skirt, a pair of wedge sandals, a black halter-neck tank top and, if her exposed skin was to be believed, no bra. His mind was blank. His little sister should not be wearing those clothes. His little sister should not have legs so long and slender. His little sister should not make the most primitive part of his id jump up and pay attention. Conclusion: This was not his little sister. But that was impossible. As her (long, perfect) legs twisted together and her (smooth, pale, perfect) shoulders sagged, a little of his baby sister crept back into the image. His eyes, drawn at first to her calves, slid slowly up her body. He willed his eyes to close, his voice to reprimand her for trying to grow up too fast, his more basal instincts to sit down because that was his little sister. The hormonal side of him did not do him the courtesy. The cubicle suddenly felt ten times smaller and ten times hotter.

"There's a party at Mark Jackson's house tonight..." It was Friday. Harry was staying with their mother in the hospital. Dexter was to keep Debra safe. He was to abide by a different code tonight.

"No. Dad said no parties."

"He meant no parties at our house."

"No."

"You can't stop me."

"I'll call Dad."

"No you won't. You'll have the house all to yourself to do some precious study." She sneered.

"I will."

"Please Dex?" Damn, she'd said please. For some reason, perhaps the possibility of seeing her in that outfit again, he was unable to deny her.

"Fine. But I'm coming with you."

The music was audible from two streets away. As far as Dexter could tell, this party was no more threatening or dangerous than any other party he had attended. He could already see some of his peers stumbling onto the front lawn, bodies overloaded with alcohol. Away from Debra in those clothes his mind had reverted to the usual cool, calm environment Dexter called home. He'd spent the rest of the afternoon trying to justify the party to himself. Debra hesitated beside him. Her hair was sleek, shiny and straight. Some subtle, enticing perfume emanated from it as a faint breeze broke through the humid Miami night. She wore, Dexter guessed, very little make up and was without her glasses. She looked down, self-conscious.

"You look fine." Dexter assured her, hoping he'd guessed right.

"Thanks, Dex." She mumbled. This was her first high school party. From her point of view, this was a momentous occasion. In her new clothes, no one could accuse her of being a tomboy. Dexter's presence soothed her, and she was determined not to be a coward in his presence.

"Deb, if you don't want to go, I can take you home."

"No, no, I want to stay." Her voice was sure, though there was a waver of uncertainty.

"Right, um, so, don't leave with anyone apart from me. Don't take a drink you haven't opened or poured yourself. Don't have too much alcohol. Don't be alone with some boy you don't know. Don't be alone with some boy you do know."

"Yes, sir." Deb rolled her eyes and they walked together into the party. They were soon separated by Deb's determination not to be a complete social reject.

In the early hours of the morning, the party was still in full swing. Dexter observed the can of beer in Deb's hand appeared not to have changed from her original can. He had been tracking her, under the pretence of mingling with his classmates. People generally liked him, although he was still learning how to fake human interaction, and he got along fine as long as no girls hit on him or tried to flirt. A group of jocks, full of testosterone and alcohol, had pushed their way into the room. Dexter's pulse quickened, his Dark Passenger awakening as he noticed the particular attention Deb was receiving from the jocks' leader. Smoothly, he slid closer to the group, barely able to hear the conversation. He heard the jock use a cheesy pick-up line, and Deb's giggle. After a few minutes, the jock managed to hit on a sore subject for Deb.

"So I'm surprised your daddy let you out here tonight." That was all it took for Dexter to smoothly place a hand on Deb's shoulder from behind.

"Excuse us." And just like that, Dexter whisked Debra upstairs (the strictly off-limits upstairs). He didn't need to say anything. Neither did she. Her face crumpled as she tried not to cry. It had been stressful for the whole family. Their mom was sick (dying, although no one wanted to say it), their dad was rarely home (either at the hospital with their mom, at work, or taking Dexter hunting). Debra was all alone. Except for Dexter. She couldn't hold her emotions in anymore, flinging her arms around Dexter as the sobs broke loose from her chest. Although uncomfortable, even Dexter realised what he was meant to do.

"It's okay." He murmured. "We'll get through this. I'm here for you." Generic, perhaps, but appeasing. His arms around her waist, hers around his neck. She was content to feel to comfort afforded by her brother.

"Thanks, Dex." She mumbled into his chest. "Just lemme sit down a minute."

He opened the door of a bedroom for her, ghosting his hand over the small of her back as she passed. She flopped down on the bed, tired and slumped. Dexter tried hard not to notice the slope of her shoulder, the curves outlined by her new party clothes, the moonlight shining off her legs. Deb swept her dark hair away from her face, revealing a slender throat, blue veins almost visible under her pale skin. He felt an undeniable urge to touch, but touch what, he pondered? One tiny part of him begged to be allowed to ghost over her breasts, squeeze her hips, worship her body. A much, much larger part of him wanted to trace her veins and see the blood running within them. Without making a conscious decision, his hand settled on the side of her throat, thumb stroking and exploring her carotid artery. His eyes were fixed on her throat, white in the moonlight. Deb studied his face, breathing shallow. He could feel her pulse accelerating. His strokes were smooth and light, nimble fingers causing an unanticipated response in Debra. She made a tiny, almost inaudible sound in the back of her throat. It triggered the other part of his brain. The one that was held captive by his hormones. His eyes met hers. His hand stilled. The instinctual sides of the pair recognised something in the other's eyes. Dexter's hand moved from her throat to her shoulder, before smoothing over her back and coming to rest on her hip. Debra tilted her head towards him slightly, unaware she had even moved.

"Freaks." The jock had entered the room, unnoticed. His face pulled a sneer and he retreated, unsure of what he had just witnessed. The tension remained. In fact, the tension remained through the car ride home.

"We should go to bed." Dexter mumbled. He was fairly sure what had happened tonight was not sanctioned by any code of Harry's. Deb nodded, still silent. Somewhere around 4, she tip-toed into Dexter's room. Perhaps she should have had the opposite reaction, but Dexter felt safe, especially when she was all alone at night. He was sleeping on his side, arms positioned perfectly to hold her. She slid in next to him, still in her party outfit, and eventually drifted to sleep. When she woke in the morning, Dexter was still asleep, one arm around her waist holding her to him. She could feel every plane of his body against hers. She could feel every part of him – his chest moving up and down steadily, his legs shifting against hers. And... Her cheeks flushed. It was definitely time to go.

The fourth time was the night Harry died. Dexter had been waiting in the hallway of the hospital, he had already made his peace with Harry. Debra was still with him, holding his hand and trying to regain a lifetime of lost time. The last thing her father saw was her face. Debra was inconsolable, although Lieutenant Matthews, Harry's closest friend, did his best. Harry had asked of him to keep an eye on Deb. Debra stayed the night with Dexter. Dexter, now 24, understood much better now what a brother was, and what function he should fulfil for Deb. Or, perhaps, he did not. He took Deb home, sat with her on the couch, held her as she sobbed, marvelled at the emotion he did not understand. Eventually, she cried herself to sleep and Dexter, Harry's last request to look after Deb fresh in his mind, couldn't bring himself to move her. He eventually arranged her on the couch, with a pillow under her head and a spare blanket covering her body. As he turned to go to bed, her hand moved lethargically to hold his.

"Don't go." She murmured, almost asleep. He sighed. He understood her pain, and her shallow, even breaths and open, relaxed expression reminded him of her as a child. He could not hurt her by leaving (and not just because of Harry's teachings). He couldn't sit on the floor next to her all night. Neither could he fit on the couch (well... not in the way that a brother and sister would fit together). So he scooped her up, blanket and all, and carried her to his bedroom. He cradled her against him, one hand behind her head, holding her to him, the other wrapped loosely around her waist. She returned his embrace, head against his chest, legs entangled with his.

The role of son was one of the earliest he learned. His conscience was something that he lost over time. In his younger years, he had an ever-dwindling sense of what was right and wrong, usually based on how the people he valued would react ("Why didn't you, Dex?" "I thought you and Mom wouldn't like it.").

The role of brother was harder for him to understand – he had this instinct to protect Deb at all costs, yet simultaneously she sometimes irritated him beyond belief. She tempted him in all kinds of ways, confused him, drove him crazy, yet always he learned that he should please her. The feeling went beyond learned behaviour, giving him a standard by which to judge his actions. As he grew from child to adult, his feelings for her would change as they changed as people. As a teenager he would forget the sacrifices he made (or didn't make) for her. As an adult he would forget until much later the undertones in their relationship, dismissing them as hormone-fuelled encounters. She would absorb them without registering what they were. Until one day, when she finally gained control over her emotions and realised that for years, she had been in love with Dexter. She didn't want to hide from him, couldn't fathom trying to keep her feelings secret and keep using other men as props. All she had to do was go to the Church and tell him...