She looks like Katherine is all he can think the first time he sees her. She walks like her, acts like her. Sometimes he even thinks she smells like her. But that is where the similarities end. Elena Gilbert her realises after he tries to kiss her is nothing like Katherine Peirce: she doesn't smile coquettishly up at him when she wants something, simpering and smiling, she scows and demands it when he's being deliberately annoying and gently asks him- with a tilt to her head and a small, heartfelt plea in her voice when he's not. He's never denied her yet.
He finds her intoxicating in the best way possible, she's like an expensive scotch and the richest blood and just enough innocent to feel like heaven all rolled into one. She makes his throat burn with hunger and his eyes cloud over with lust. She makes his fists tighten in annoyance and his mouth lift in amusement. She's enticing and argumentative, and enchanting and annoying. She dances with the devil on a regular basis and yet she still never seems to get burned; the compassion inside her - even for someone like him "I'm sorry, about Katherine...you lost her too- keeping her pure enough to attract Stefan but dark enough to spur his own blackened desires and make his mouth water at the thought of tasting her; both her blood and her body.
She knows just how to drive him to the brink of insanity, pushing and kicking and screaming to get what she wants every step of the way. She refuses to let him win against her; forcing him to see things her way, screaming at him just what she thinks of him when he does something irredeemable in her eyes and every so often giving him as slap that hits with enough impact it actually almost hurts.
She is Stefan's angel, bubbly and innocent and sweet and good when she is around him, but she's his too, his fallen angel. He sees the darkness inside her sometimes, the kind Stefan pretends not to see while wrapping her in yet another layer of cotton wool. But he sees it, and it excites him because it causes her to eyes to burn when they fight; lust and want and heat mixed into her gaze as she tries to force the disgust and betrayal shining dimly on the background to penetrate his soul as she delivers another thundering slap to his face or a stinging comment to his pride. She thrives off the hunt the same way he does, throwing herself into situations any normal human would run a mile from. He sees the thrill of it on her face as they chase down demons and fight off vengeful vampires.
She doesn't hide herself from him, he is so evil nothing she could possibly say or do would seem irredeemable around him, so she acts free; speaks her mind, lets her fists fly. If any of her little school friends saw his Elena, they wouldn't recognise her. With him she is a spitfire and a warrior who always gets her own way: he backs her into a corner; fangs bared, eyes glinting and homicidal threats spewing from his lips and she walks away without a scratch- throwing a smug smirk over her shoulder at him with exasperated words and laughing eyes. Untouchable he thinks even as his fangs long to pierce her veins and his body longs to embrace hers. But he doesn't, because as much as she pushes him, he almost wants to give in- do everything she asks and have it be his arms she walks into at the end of the day, not his brothers.
So he curbs the killing, and he never lies to her about anything, no matter how gory or how awful because he knows her and he knows she wants to know- doesn't want to be protected, can look after herself and can handle anything he throws at her. So when she asks about the lack of bodies in the area recently he offers her a long suffering sigh while he rolls his eyes at her as he flips open the fridge door- newly stocked with bagged blood, each with their own convenient little bendy straw attachment. Then he waits. And offers her a devilish smirk a few weeks later while making yet more plans to rid the town of the other pesky vamps who've been snacking on the locals. Her eyes catch his; dancing playfully; darkness and goodness and lightness and wickedness all rolling through them in a delightful mix- igniting a spark of hope in his own tumultuous orbs as she returns the smirk and ignores Stefan's mumblings in the background.