Guard Dog
Sebastian Sallow x Reader
Sebastian Sallow has never considered himself overprotective—just attentive where it matters. After all, when you first arrived at Hogwarts, it was him who showed you the castle’s secrets, who taught you who to trust and who to avoid. Looking out for you simply became second nature. So when someone else tries to step a little too close, it’s only reasonable that Sebastian reminds them exactly where they stand.
tw: dark!sebastian sallow, jealousy, crosswands duel, established relationship/friendship, he means well(no he doesn't), protective/possessive/obsessive behaviors, no use of y/n, manipulation(light/implied), reader's house not specified wc: 2.1k Read me on Ao3! lol my OG house quiz years back was Ravenclaw, then I did it again when I was 16 and got Gryffindor, did it a few months ago and got Slytherin...
Sebastian Sallow personally wouldn’t consider himself ‘overprotective’ of you; no, that sounded far too excessive. A bit melodramatic even, he’d say. If anyone cared to ask, he’d describe himself as a concerned friend–one who simply had the decent sense to look out for your best interests, when others clearly didn’t. When you first arrived at Hogwarts, wide-eyed and unfamiliar with its endless corridors, hidden passageways, whispered reputations and secrets, it had been Sebastian who stepped in. Sebastian who showed you how to navigate the ever shifting staircases, which professors to charm and which to keep your head down low, which students to keep at arm’s length, how to avoid irritating ghosts. He had made himself indispensable so naturally, so seamlessly, that it was hardly surprising you both ended up becoming best friends. Kindred spirits, truly.
Part of having your best interests at heart required attentiveness, awareness, a certain… vigilance. Sebastian excelled at all three. He practically knew you better than you knew yourself at this point. The subtle shifts in your tone of voice, the meanings behind your expressions before you even voiced them. He could tell when you were humoring someone, when you were bored, when you were genuinely interested…
That last one was why it was only natural that his ears would pick up on the conversation of the poor fool attempting to flirt with you while he stretched and prepped for his Crosswands duel. Across the room, he stretched his arms and shoulders, rolling tension out of his muscles as he eavesdropped. His gaze remained fixed on the match at the center of the room, seeming outwardly composed and entirely unbothered. Anyone watching him would think his focus was absolute. It wasn’t. Every word of your conversation carries cleanly across the room. He didn’t need to look to picture it–the way you angled your body just slightly toward the Gryffindor, the faint curve of your lips when you spoke, the polite but not entirely dismissive way you entertained him. You were being too receptive, too open.
Sebastian tells himself it’s nothing. It’s just harmless flirting. A meaningless pastime before your own duel, you’d lose interest soon enough. You always did. Lost interest and always gravitated back to him, as it should be. As it was meant to be.
Still, he continues to listen. Because of course he does. It’d be irresponsible not to! He spares a brief once-over in your general direction, immediately assessing everything. The Gryffindor–seventh year, if Sebastian remembered correctly, arrogant in the way most older students often were–leaned a little too close while speaking to you. Sebastian’s jaw tightens, just slightly.
He exhales through his nose, slow and controlled, forcing his shoulders to remain loose as he flexes his fingers around his wand. He’s fine. Perfectly fine.
Then the Gryffindor laughs, low and self-assured, “Unless your overprotective guard dog takes issue with you going out without him.”
Sebastian stills. Not visibly, not enough for anyone else to notice. But inside himself, something sharp and immediate snaps, setting into place. Guard dog. The pathetic attempt of a lighthearted joke doesn’t bother him, what bothers him is the implication behind the words. That his presence in your life is something to be worked around. The mere idea that someone else thinks they can simply…step in, so long as they get through him…
Slowly, Sebastian lifts his gaze. Not towards the Gryffindor, he couldn’t give less of a damn about him. No, his eyes land on you. Because what matters—what always matters—is your reaction. Do you laugh it off? Deny it? Agree, for Godric’s sake? Because if you entertain it, if you let that idea linger, even for a second… then this flirting stops being harmless. You choose the neutral route. A slightly uneasy, fake laugh slips through you as you wave a hand dismissively to the 7th year, as if you're waving away such a notion. The Gryffindor doesn’t take notice of the out you’ve given him to drop the subject, instead he doubles down. Continues prattling on about how you’re always around the Slytherin man, that it’d be healthy to ‘meet other people’ and ‘spend time away’ from him.
Treacherous words–ones that Sebastian has no intention of letting linger. He let the moment stretch just long enough to see how far the Gryffindor was willing to go. Just long enough to confirm what he already suspects–that he’s attempting to step in between the two of you, attempting to get in the way of everything Sebastian has worked hard to build and maintain since meeting you. The Slytherin rises to his feet. A few students look over, most likely feeling the energy shift in the room as Sebastian rolls his shirt sleeves up to his elbows. His grip tightens on his wand subtly as he walks measured, intentional, and unhurried over to you and your newest little irritation for him.
“If you’ve got something to say,” Sebastian calls, his voice smooth, carrying easily over the noise of the room, “you may as well prove it.” This time his eyes are set, locked on the Gryffindor. Anyone else would see a confident, smug smile on Sebastian’s face.
You aren’t anyone, however, and you immediately clock his expression for what it truly is: a sardonic smile with dark eyes full with the intent to harm. “Sebastian…” You say a little quietly, more in slight warning to cool it before he takes it too far. Again. He doesn’t acknowledge your light warning, whether he really heard you or not through the dark thoughts in his mind as he glares down the 7th year.
Conversations taper off, the duel that was happening in the middle of the room stops abruptly as well. Attentions turning toward the three of you as Sebastian’s challenge settles into something real. The Gryffindor huffs a quiet, mocking laugh, an arrogant grin on his face as he straightens his posture to look Sebastian in the eyes. He glances at you as if to gauge your reaction, then steps forward to Sebastian with a shrug that borders on careless. “If that’s what it takes.”
They take their places opposite each other in the center of the clock tower courtyard, wands raised. Lucan nervously flits his eyes between the two competitors for a second before quickly switching back into his upbeat, excited demeanor as he announces the duel is on. For a heartbeat, everything stills, until the Gryffindor man shouts “Expelliarmus!”, firing first, quick and confident.
Sebastian deflects the spell without effort. A flick of his wrist, clean and precise, the spell glancing harmlessly aside as if it were nothing more than annoying gnat hovering around him. The crowd erupts into cheers and competitive yells as they pick sides, some students even placing bets on who will win. Sebastian doesn’t counter immediately, his eyes never leaving the other student as he walks towards him. The Gryffindor presses again on the advancement, “Diffindo!” Sebastian side-steps the sharp slash. His motions are fluid–controlled, almost elegant–as he aims his wand towards the Gryffindor, “Levioso.”
The Gryffindor attempts to dodge but is caught mid-step, enough to break his footing and disrupt his rhythm, lifting him above the ground. Sebastian shows no mercy as he launches Confringo back to back, each spell landing on the poor Gryffindor and sending him flying backwards towards some wooden crates stacked against the stone wall near the back gate. Before the Gryffindor can regain his senses, he’s dragged back towards Sebastian, his brain hardly registering the Accio that leaves the Slytherin’s mouth.
A furious grunt escapes the Gryffindor as he fights against the spell, dropping to his feet and quickly side-rolls away from Sebastian before coming back up with a quickly aimed Bombarda. The crowd gasps a little, bombarda was off limits since the last time it was permitted, a duel ended with two students getting sent to the infirmary in the Hospital wing. Sebastian grins wickedly, knowing he’s getting under his skin, making him sloppy in his attacks, “Protego… stupefy!”
“Protego!” The Gryffindor counters his stupefy, but Sebastian is quick in sending his own Diffindo towards the 7th year. It knicks the Gryffindor’s robes, grazing his arm as the brunt of the spell slices into the ground next to his feet. A few murmurs arise near you, a group of students debating whether Sebastian missed, or meant to do that. You know the truth, as does his competitor, Sebastian didn’t aim to injure the man. It was a warning. A warning to the degree in which the poor guy is outmatched. The murmurs from the group of students next to you go silent, as if they finally clocked that this wasn’t a simple duel of egos between the two. It was a lesson.
The two men are their own lightshow as they go toe-to-toe, never surrendering to the other. It had to be the most intense fight Crosswands has seen all year.
The two men glower at one another while they pant, attempting to catch their breath.
Sebastian glances at you. Just for a second; long enough to make sure you’re still paying attention. Of course, the Gryffindor notices, and glances between the two of you, before looking down at his tattered House robes. That famous Gryffindor pride must have taken over because he straightens, his jaw tight as he fires off a series of stronger spells. Less controlled, but there’s more force behind them than necessary.
A mistake that Sebastian notes, and doesn’t hesitate to feed on. He steps into the attack, countering easily with Protego, working on closing the distance. “Expelliarmus!”
The Gryffindor’s wand rips clean from his grasp, skittering across the clock tower floor as the crowd lets out a crescendo of Oohs, some students cursing out loud at losing their side of the betting.
“Levioso,” Sebastian says tauntingly, “Accio.” He brings the student close to him, looking smugly at the Gryffindor as he levitates in front of him, kicking his feet in a furious protest.
“Damn you, Sallow,” The Gryffindor hisses out, “You’re a right bastard, y’know!?”
For a brief moment, while he watches the man struggle, Sebastian contemplates exposing the darker side of magic that he’s privy to. Crucio would set this arrogant foolish student straight. Maybe, to send a final message to all of Hogwarts, he should use Imperio… have him reenact what he made the goblin that almost attacked Anne do.
A dark shadow passes over Sebastian’s face, one that makes the Gryffindor hesitate in his flurry of insults–a small inkling of dread creeping up his spine at the look on the Slytherin’s face.
“Sebastian! That’s enough!” Your voice breaks through the darkness swirling in his mind, he blinks away the thoughts before looking your way. You’re already through the crowd, walking quickly to him. His heart skips a beat at the sight. Nevermind your worried expression at his antics, he likes that you get concerned for him anyway.
“....Fine. For you.” Sebastian sighs, turning his attention briefly back to the dangling Gryffindor.
“Just remember; this dog bites.” He mumbles it low. The Gryffindor’s eyes widen slightly, he opens his mouth to sputter a reply but is cut off by Sebastian cheekily casting descendo onto him.
“Seriously, was that necessary?” You ask him, as the poor student groans in pain, some other students are already at his side offering him wiggenweld for his injuries. “What?” Sebastian asks innocently, as you hand him a wiggenweld potion, which he accepts graciously. “Now you’re just being mean.” “More like making a point, pet.”
You roll your eyes as you two walk out of the duelling club, him leading the way to the Room of Requirement so you can patch him up and have some privacy, and to scold him for his antics.
Sebastian settles against you like he belongs there–like there was never another option–as you thread your fingers loosely through his brown locks. After you were able to give him a ‘thorough check over’, he was adamant he needed rest before he tackled you onto the bed, promptly resting himself on your stomach, while his muscular arms wrapped themselves upwards around your waist.
“You didn’t have to be so rough on the lad, I wasn’t planning on going to Hogsmeade for butterbeers with him.” You smile softly, continuing your ministrations on his scalp. “It was a matter of principle.” He replies lazily, readjusting his position so he’s able to wrap around you more thoroughly, earning a soft bubbling laugh from you, as you two are practically spooning by the time he’s done. “What principle might that be?” “That you’re mine,” he murmurs, voice soft against your skin, “and I don’t share.” This dog bites.





















