This chapter started as part of this series, became a one-shot and is now back in the series because I took out the Severus/Regulus during a re-write. Regarding Snape smoking, I always see him as a smoker. Probably something to do with the yellow teeth. Full disclaimer: I haven't managed to quit yet either.

Severus was getting better and better at Occlumency and Legilimency, so good it almost scared him. He didn't even need to say the spell or raise his wand anymore to get at least a glimpse of most people's minds. All he had to do was get them to meet his gaze, even for a brief moment.

It was nothing like the real thing, of course, just skimming over the top and being able to know if they were telling him the truth or lying through their teeth. It was basically the equivalent of a very good knowledge of how to interpret body language. But it was a rare skill nonetheless and something to be proud of. An achievement. A weapon. He knew that in a weird and twisted way this was the psychological equivalent of undressing someone with his eyes, a secret sort of violation of privacy that went even deeper because it relied on truth not imagination, but that wasn't the kind of thing that bothered him.

Bellatrix Lestrange's eyes betrayed a lot. Her thoughts, when not strictly regimented, tended to escape their compartments and drift around her head completely at random. So when he tried out his little trick on Regulus Black he had expected his eyes to lead to a more neat and disciplined sort of mind. However, he was surprised to find that it was just as chaotic, and even though he utterly detested him he had to express a grudging admiration for the way that he kept it all under control. He supposed that he shouldn't have been so surprised when he was essentially looking behind the same colour and shape of eyes, even though Regulus only resembled Bellatrix in superficial ways.

Of course, he never went very deep. He could tell that Bellatrix had more than an adequate knowledge of Occlumency and would put up shields instantly if she felt threatened, and he wasn't actively suicidal. So he was sure none of them had even felt the slightest hint of him poking round their heads, right up until the moment Regulus Black pushed him out of his in the middle of a Death Eater meeting after they'd had a particularly "special" spat in the corridor.

The boy gave no outward appearance of being bothered all the way through the rest of the meeting but once everyone had begun to disperse he walked up. Severus tensed. He fully expected some sort of tantrum but it didn't come. Instead, Regulus simply stared at him, obviously thinking hard.

"I want you to teach me Legilimency and Occlumency." Regulus said it without so much as a scrap of politeness, standing there with one hand on his hip and the other holding his wand at his side, the very picture of the perfect little pureblood heir he obviously wished he was.

Severus rolled his eyes and picked at the cuticle of his left index finger in an attempt to look nonchalant while he resisted the ever-rising urge to punch Regulus in the jaw. "What makes you think I can do either?"

"Do you think I haven't felt you rummaging through my mind as if it belongs to you? You're not as subtle as you think. Or smart, if you couldn't guess."

Damn.

"I won't teach you," said Severus sullenly and walked away, or at least he tried to. Regulus had the quick reflexes of a Seeker, after all, and he'd grabbed Severus's arm uncomfortably tightly before he even managed to turn around.

"What, are you scared I'll be better at it than you are?" The accompanying grin was surprisingly feral, and Severus had never been so aware of how much Regulus resembled his arrogant bastard of a brother in more ways than just dark hair and high cheekbones.

"No. I'd rather not waste my time. I'll admit you've got the sort of mind that could handle the concept of Occlumency, putting everything in little boxes, but in reality you would trip at the first hurdle. And Legilimency? That takes an entirely different level of subtlety, a higher one. You'll run in without an ounce of delicacy - "

"I'm not my brother," snapped Regulus.

Severus smirked. "See. That's what I mean. No control. That tongue of yours will get you in trouble, just like your idiot sibling." He wrenched himself out of Regulus's grasp and didn't give him the satisfaction of looking back.

Severus had last slept in his mildewed room in the house at the bottom of Spinner's End over a year ago, and he didn't miss that life one bit. The bedsit flat he was renting over a drinking den in Knockturn Alley served him well - a quick silencing charm dealt with the shrieks and cackles of the patrons below (he'd never seen them and didn't care to) and then he could sit alone and read or whatever else he felt like doing. He wasn't happy there, but he didn't dwell on that because the inevitable destination of that train of thought had dark red hair and bright green eyes and made his head ache and his guts twist.

He stubbed his cigarette out in an abandoned mug then set up his cauldron, conjured a flame beneath it and got to work on a sleeping draught. He still had his Advanced Potions textbook with his frantic annotations but he'd committed every detail to memory. He had to. He couldn't bear to look at it and remember all the times he and Lily had tried out new methods, messing around with potions ingredients, laughing when they went wrong and smiling when they got it right.

He'd gotten as far as slicing the valerian roots when an unwelcome presence announced itself.

"Hello," said Regulus Black, shutting the door behind him.

"How the hell did you get into my flat?" shouted Severus. "Get out!"

"No," said Regulus, calm and infinitely smug even when being threatened with a knife covered with squashed valerian roots. "Honestly, silencing charms? How are you supposed to hear Aurors or that damnable Order coming for you up the stairs if you've got those all over the place?"

"I have other precautions."

"Yes, and I got through them. I have fantastic sneaking-around skills, it's the kind of thing you have to perfect living with my family, and I know your landlord. My mother has a lot of business with him, actually. Sometimes connections are important. Ugh, it stinks in here. Have you started smoking those Mudblood cigarette things again? They're so disgusting."

"Are you here to annoy me to death or do you actually have a reason for breaking and entering?" sneered Severus, ignoring the question. He had started smoking again, that much was true, but his occasional Muggle habits were none of Black Minor's damned business. "If it's about those lessons, then I've already told you, I'm not helping."

"I can pay you," said Regulus quickly.

"I don't need your charity." Severus tried not to look at the cheap furniture or the perennially peeling wallpaper. But Regulus looked simultaneously disappointed and defiant, and Severus had to admit that he was intrigued by the sheer level of persistence he was displaying. "Look," he relented, "why do you want to learn Occlumency? Is this just a childish whim, or have you got a definite objective in mind?"

Regulus looked a little unsettled. "Well... to put it bluntly, you aren't the only person in my current social circle who can read minds. I'd rather not leave myself open to trouble. So will you teach me?" Regulus pulled a galleon from his pocket, throwing it up in the air and catching it again as easily as breathing.

Severus stared at the glittering gold coin intently for a moment. "Fine," he said finally, exhaling dramatically. "Just so long as you are aware that you can't learn everything today. It takes a very long time, a lot of concentration, and a lot of practice."

"Start me with the basics then."

"Fine. Tonight, I am going to get into your mind and memories, and you have to extricate me by any means necessary - eventually you'll have to do it using only the power of your mind, but - " he looked at Regulus distastefully " - that might take a while. So at first all you have to do is figure out how to resist the onslaught."

Regulus nodded. "Try me."

An hour later, Severus would have been almost getting bored of free access to Regulus Black's mind if it weren't for the adrenaline rush. He pushed through memories yet again (his mother and Sirius shouting at each other, a house-elf making cocoa, his first kiss, all silly little things) then snapped back into reality, gasping for breath. Regulus was lying sprawled on the floor panting, mouth slightly open and a pink tinge to his cheeks.

"You're hardly even trying. If I didn't know better, I'd say you actually enjoy me rummaging through your mind as if it belongs to me."

Regulus glared at him from the floor. "I don't like your tone. What exactly are you implying?" He got up and brushed dirt off his robes, nose wrinkling up in disgust in a way that combined with his fragile bone structure made him look disturbingly like Narcissa even without her freak-of-nature golden hair. That was the Rosier influence, no doubt, or one of those genes that sprung up when no-one was looking. Severus felt that you really had to admire that sort of sneakiness in biology.

"Oh, nothing, nothing." Severus didn't even try to keep the self-satisfied look off his face. "Ready to try again?"

He pouted, actually pouted. "Of course. It'll take more than anything you can throw at me to take me down."

"Fine. Legilimens!"

For a moment he was inside another memory, but before he could even register what it was there was a force pushed him back. He sensed himself fall to his knees with an arthritic-sounding crack but it was so far away it was as if it was happening to someone else.

A man shouting. A woman crying. A slap across the face that stung like fire over his cheeks and nose. Staring at the most beautiful creature he had ever seen. Hushed whispers. Spitting an unforgivable word.

In an unconsidered motion, something from far beyond his conscious mind, he punched Regulus Black in the nose.

He missed, hit his pearly teeth which grazed his knuckle and then he felt blood on his hand, but it mostly wasn't his own, and the fighting psyches of Severus Snape and Regulus Black settled back into their own respective minds like dogs in the pit being called back to their masters' heels, still tense and ready to spring back into the fray.

Severus wanted to shout, demand to know what Regulus had managed to figure out from that collection of vague shades and whether he was now one of the biggest threats to him he knew, but all he managed to do was mutter "that's my personal business. You had no right. And I thought you didn't know Legilimency."

Regulus was back on the floor again, blood all over the front of his expensive robes and looking more scared than defiant, and Severus allowed himself a little shiver of victory. But then the smirk was back. "I don't. I'd like to pretend I'm some natural savant at it, but if I'm honest it was a reflex reaction. It was like being a caged animal."

I hate you, I hate you, I hate you.

"What exactly did you expect me to do when you were demanding I actually try to get you out of my mind? Play nice?"

"Playing nice? Don't kid yourself. I could kill you before you even knew I was there. I'm done with you."

Regulus said nothing, just stood up shakily, wiped more blood off his mouth with his sleeve then stalked off, slamming the door behind him. Severus groaned and collapsed on his bed, staring at the cracks in the ceiling. He reached for his packet of cigarettes but Regulus had reminded him that it was a dirty Muggle habit, and Lily had always hated it too... he settled for wishing Lily would get the hell out of his head.