A/N: Obviously AU. Ari never killed Kate, and she and Ziva actually met.
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"I can't do this."
Those four little words send Ziva's world crashing down, her guard set back up as high as the Wailing Wall. She looks into the red head's eyes, the pain she feels hidden from her gaze as she looks over at her almost lover. Kate has her lip caught between her teeth, eyebrows furrowed as she debates what she should do next. Ziva can see her mind's battle playing across her face, and she wonders what the NCIS agent is going to do next.
"Why?" The tiny little word slips between Ziva's lips before she can stop it, and though she berates herself for letting her guard slip back down even the tiniest bit, she finds herself wanting to know the answer.
"Every time I look at you," Kate begins, pacing back and forth as she runs a hand through her hair. Ziva watches as the strands catch the light, glinting with that beautiful red she'd loved since she'd first set eyes on it. "I see… him."
Ziva's eyes widen in understanding, continuing to watch as Kate's torment plays out right in front of her. A part of her is hurt, the part she'd sworn she'd locked away when she'd joined Mossad. The part that still allowed her to want and desire and need. "I am not Ari."
"I know that." Kate's voice is strained, pain seeping through as she fights herself over the fact that what she wants is the one thing she can't possibly have. "But I can't. How could I do that to the team? To Gibbs?" Kate sighs and looks away as Ziva takes a step towards her. The Israeli lifts her chin with a fingertip, gazing into her eyes as she whispers the words Kate knew she would say. "They would not have to know."
Kate is tempted, as she knew she would be, as she locks eyes with the beautiful Mossad agent. She knows she's dancing with the devil with every passing second that she doesn't say anything. She knows its wrong that her heart rate picks up as Ziva's lips inch closer to hers. And she sure as hell knows that it shouldn't feel this good as Ziva slips her tongue into her mouth, teasing out a moan from her throat that she knew shouldn't have even been there.
But in the end, her instinct wins out over her conscience, and she pulls Ziva closer by the waist. Her hands run through the Israeli's long dark hair, and she leans her head back to allow her to kiss a path down her neck.
It shouldn't feel this good, but that didn't change the fact that it did.