Irreplaceable

Summary: KateTonyZiva. Tony never loved anyone but Kate but after her death fate pushed him and Ziva together. Five years on they are expecting their first child together but can Tony really move on from Kate for good? Tate with elements of Tiva.

Don't worry, I haven't gone over the dark side and started shipping Tiva, hopefully you can see that from the Tiva angst and Ziva bashing in this fic. I'm not sure what I really think of it but the plot bunny had been pestering me for ages so I had to write it! Reviews are appreciated!

Please ignore any spelling errors, my computer has a virus and the only other computer I have access to doesn't have Word! Xx

Ex Mossad agent and now full time NCIS special agent Ziva David looked up from her desk as she heard her boss calling her name as he approached.

"Gibbs?" She asked, swivelling slowly in her chair as she manouevered her five month baby bump.

"I think it's time you went on maternity leave, Ziva." Jethro Gibbs told her, in a voice that told her that she wasn't expected to argue. "I've been talking to the Director about it and she agrees with me."

"But Gibbs..."

"Don't 'Gibbs' me Ziva, I'm serious about this. Tony will be too." Gibbs said, refusing to take no for an answer. He was barely over the death of one of his most promising agents and that was over five years ago now. He refused to lose another agent in the same way that Caitlin Todd had been taken from the team.

"Tony will be what?" Agent DiNozzo asked, appearing from the open elevator doors and heading for his desk.

A small smiled played across his lips but he knew he should be happier than he was and felt guilty for it. Sometimes he wondered if he really was just stringing Ziva along because he knew that his own eyes did not reflect the same joy that hers did whenever they looked at each other. Somehow the years had sped by and somehow they were still together. The time when they got together was hazy to Tony and not because they were so joyous but because he genuinely couldn't remember. After Kate's death he had started drinking much more heavily than he ever had before as he could think of no other way to drown his sorrows. He had lost the one woman he could have seen himself having a future with and commiting too. It was a cruel twist of fate that she had been taken from him before he could tell her any of this, especially when he was almost convinced that she returned his feelings.

He knew he should count himself lucky that he had found another woman he could love and have a future with but the sparks and chemistry that he had had with Kate just weren't there. Now she was pregnant with their first born but he knew he wasn't as excited a he should be. The months were speeding by rapidly now and in three weeks time, if everything went according to plan, he would be the proud father of Ziva David's baby. Gibbs seemed to sense a lack of enthusiasm on Tony's part and many times Abby had asked him if he was happy. Of course, Tony faked a smile and told everyone that everything was perfect. He knew that he couldn't hurt Ziva, especially now she was so close to entering the thrid trimester of her pregnancy. Deep down he also knew that Kate wouldn't have wanted him to leave Ziva when she needed him the most.

"Gibbs wants me to go on maternity leave, from now." Ziva said, facing her partner. "Tony?" She asked when he didn't reply, Tony was lost in his thoughts.

"Oh, right, well he's right Ziva, you've got to look after yourself and the baby." He told her, Gibbs nodded from across the room.

"That's what I told her."

Ziva sighed. "Fine, I'll finish this week and then I'll go on maternity leave. Does that make you happy?"

Tony nodded, but it would take a lot more than that to make him truly happy.

"Hey Abby," Tony greeted, entering the lab and crossing the room to where the Goth was typing manically at her computer.

"Tony!" She exclaimed, sitting up and pulling him into a tight embrace. Since Kate's death, Abby and Tony's friendship had become more dimensional and they were much closer than they had been before. It was one of the few good things that had come out of Kate's early demise. "How are you? And Ziva?" Even after the years had passed and Ziva had become a permenant fixture at NCIS, Abby still said her name as though it was something particularly unpleasant that she didn't want to think about.

"I'm fine, she's fine. She's going on maternity leave on Friday. Gibbs doesn't want her working anymore, he thinks it's bad for her and the baby." Tony explained.

Abby nodded. "And you agree?" She asked.

Tony shrugged. "Yeah, I guess it's for the best. She'll go stir crazy at home though."

"As if she wasn't already." Abby muttered darkly, under her breath.

"Ab, I wished you'd like her more." Tony said, trying to hide his faint amusement at the Goth's hatred for Ziva.

"I can't help it Tony, I have tried. I still see her as Kate's replacement and I still miss her."

"I know," Tony said, looking at the floor sadly. Five years had done little to numb the pain and grief he still felt. "So do I." More than you know, he thought of adding but he knew how intuitive Abby was. That was why seeing him with Ziva was so hard for her, she had always believed that somehow he and Kate would end up together, picket fence and all.

"How was work?" Were the first words to exit Ziva's mouth as Tony returned home to their apartment on a rainy Tuesday evening almost seven weeks later.

"It was fine." Tony said a little suspiciously, since going on maternity leave Ziva had become almost obsessed with what was happening at NCIS. "How was your day?"

He sat down next to Ziva on the sofa, her bump was even more noticeable now even under her baggy blue NCIS sweatshirt that the pair of them could have fitted into.

"Fine." Ziva replied. "I just don't think I've ever been this bored in my life."

"You won't be saying that in a few weeks time Ziva, not when the little one is born." Tony said.

"True, I just can't wait for her to be born." Ziva said, leaning back against the sofa and placing both hands on her inflated stomach.

"Her?" Tony asked, his eyebrows raised. Neither of them had wanted to know the sex of the baby, they wanted it to be a surprised when the child was born.

Ziva shrugged. "Just a feeling I have."

The following Wednesday morning Tony was about leave for work when Ziva exited the bathroom.

"Uh, Tony?" She muttered sleepily. "Unless I'm very much mistaken, my water's just broke."

Acting on the adrenaline that was seeping into his bloodstream, he carried Ziva into the living room and helped her onto the sofa. This could not be happening, he had to get to the hospital before the baby was born. How was he meant to do this by himself?

"Ziva," He said softly. "We need to get you to the hospital."

She shook her head, her whole body writhing as the contractions came. She screamed out in pain.

"Tony!" She shouted, gripping his sleeve. "The baby is coming, right now!"

Panic said Tony's body into overdrive and he ran for the phone, dialling the hospital and demanding that a midwife from Bethesda be sent out immediately. He did as he was told by the midwife on the other end of the line and ran a large bowl full of hot water and found as many towels and washcloths as he could. He knew he should be by Ziva's side, holding her hand and telling her everything was going to be okay but he knew the preparations for the baby's birth had to come first.

As he waited for the hot water to come out of the tap he looked out through the kitchen window. Instead of seeing the street outside or his relection in the glass he saw Kate. It was as if she was really there, right with them when he needed her the most.

"Kate," He sighed softly under his breath. She looked just as beautiful as ever, standing outside his window with that familiar half smile on her face. Tony's heart gave a lurch which he never got from looking at Ziva. His love for Kate was a whole different type of emotion compared to what he felt for his pregnant girlfriend.

The hot water cut in, causing Tony to draw back in his hand in surprise. When he looked up again Kate was gone but he knew it was a sign. She believed her could do this and her faith in him spurred him on. He went back through to the living room and squeezed Ziva's hand, pressing a gentle kiss to her moist forehead.

"It's going to be okay, Ziva." He told her. He thought of Kate once more. "I know it will."

Although it seemed like an eternity to Tony and Ziva, the midwife from Bethesda Hospital arrived so after and was quickly ordering Tony around. He was only too pleased to help, although he may not truly love Ziva he still did not want to see her going through the pain of childbirth. The sooner this was over the better, for both of them. Tony hoped the birth of their baby would help to cement his relationship with Ziva because he could think of no other solution that would work.

The time between Ziva's contraction was becoming shorter and shorter. The midwife asked Tony for the towels and he passed them to her.

"Ziva, you're cervix has dilated now, I need you to push now okay?"

Tony and Ziva both took deep breaths simultaneously. Finally the midwife saw the head appear and slowly the baby was born. The midwife wrapped the baby up in one of the towels and held her out to Ziva who smiled happily at the bundle in her arms. Tony smiled too but he felt underwhelmed, maybe if he held their daughter.

"Tony, do you want to hold her?" Ziva asked, sensing some discomfort coming from him.

"Thanks." He said, holding the bundle in his arms and looking down at the small child. The baby looked a lot like both of them, and Tony couldn't help but feel his heart lighten slightly as the baby smiled up at him. "She's beautiful." He said.

Ziva smiled. "I know. What are we going to call her?"

Tony knew, he knew what he wanted to call her, he wondered what Ziva would think.

"Caitlin," He said softly.

"Sorry?" Ziva asked, not hearing him clearly.

"I said, I'd like to name her Caitlin."

"Oh. Okay." Ziva smiled, too happy to argue with Tony over the fact that he was naming their child after his only true love. "Caitlin it is." She agreed.

As Ziva watched Tony with the baby she realised that no one was ever going to replace Kate Todd in his heart.