Disclaimer: I don't own any rights to the show or characters of Hawaii 5-0. I'm only borrowing them for a while.

This is not my first fanfiction but is my first Hawaii 5-0 fanfiction and my first one here. I'm a huge Steve/Catherine fan. I think they have great chemistry and wish the show would do more with them.

I don't plan for this to be a long story but then again I can tend to get long-winded so no promises. I hope to update every few days but we all know how real life can get. I'll do my best.

Summary: Catherine's past collides with her present. Is the love she and Steve share strong enough to survive it?

This story is set in early 2014. Everything on the show has happened. Kono is back.

I don't think we've really heard much about Catherine's family. I can't remember if it's ever been discussed on the show, aside from her telling Grace that her dad was in the Navy too. But for the purposes of my story, Catherine's father is an Admiral in the Navy. He and her mother are still married. She has one brother, Ethan, who is 2 years older and one sister, Kelsey, who is 13 years younger.

Five-0 Headquarters – Early Friday Afternoon

"I know I'm missing something Cath. I just can't put my finger on it." Steve scowled as they walked down the hallway toward the Five-0 offices. "It's just not sitting right in my gut."

"Are you sure that isn't the two foot long meatball subs you just ate at Ba-Le," Catherine teased him once again for the sheer amount of food he consumed at lunch.

"Hey, it's your fault I didn't have time to grab more than a Goji berry energy bar for breakfast," he grinned at her, completely unfazed by her jab. Steve McGarrett had a huge appetite – in all aspects of his life – something Catherine knew well about him so her teasing didn't faze him.

"And how exactly is it my fault?" she scoffed good-naturedly as they turned the corner, but she lowered her voice as they approached the office door. "You were the one who wouldn't let me out of bed until after eight."

Steve grasped her around her waist and pulled her against his side. He leaned down and brushed his lips against her ear. "You slept in the nude last night Cath. You can't expect me to wake up to you naked and not take advantage of that."

Steve felt Catherine shudder softly at his soft words, clearly remembering the way he woke her, then worked her, before finally letting her stumble out of bed with barely enough time for the two of them to shower and get to work. Secretly satisfied with her reaction, Steve chuckled under his breath and released her.

She turned her head and scowled at him. "You don't fight fair, McGarrett."

He flashed her a cocky grin. "Never said I did, Rollins."

Steve pushed open the glass door to the Five-0 offices and stood back to let Catherine enter before him. The scent of her perfume wafted into his nostrils as she walked by and, now that he was done teasing her, it made his stomach clench. He loved working with her every day now that she was officially a part of the team, but it did make it difficult to concentrate sometimes.

Fantasies of spreading her out on the surface table and having his way with her had consumed his thoughts more often than he'd like to admit. Not that he'd admit it to anyone but himself of course. In fact, he'd had to resort to standing next to her recently in order to not see her and the table in his line of vision at the same time. He was going to have to do something about that fantasy soon.

Steve watched her walk toward Chin and Danny, who stood around the surface worktable talking, and wished they could all just call it an early day. But they needed to solve this robbery homicide case before any of them could take off.

"Hey, any updates?" Steve asked as they approached.

Chin shook his head. "Waiting on ballistics from Fong on the bullet casing they pulled out of the wall at the bank." He gestured to Kono sitting in her office. "Kono is just finishing up the paperwork on that kidnapping case from last week."

"Where have you two been?" Danny eyed them suspiciously.

"Lunch, Danny. You know what lunch is right? Every one of us is not only entitled but required by law to take a lunch."

"I'm well aware of the labor laws Steven." Chin chuckled and shared a look with Catherine.

She jumped in before Danny could start on the roll she could sense was coming. "I'm going to help Kono."

Steve smirked and his eyes followed Catherine as she walked away.

"The two of you just seem to disappear together a lot in the middle of the day with no word on where you've been," Danny continued as if he hadn't been interrupted.

"We take lunch every day Daniel. We invited you to come along if you remember. You declined in favor of a hot dog from the cart downstairs." Steve shuddered at the thought of what Danny tended to lean toward for lunch.

"Lunch doesn't take…" Danny looked at his watch. "Two hours? You do realize that playing slappy tickly during work hours is frowned on by the higher ups."

"Watch it Danno," Steve warned quietly. He didn't mind Danny's teasing, but he drew the line at anything untoward being insinuated about Catherine.

"Lighten up man," Danny chided as he punched Steve in the arm. "You know I'm just giving you shit. Catherine is way too professional to let you manhandle her during work hours. I'm still amazed she lets you do it during off hours."

Steve finally smirked and shook his head, unable to stay mad as his partner and best friend. Steve knew the entire team, Danny especially, had the utmost respect and love for Catherine.

"Enough with the wise ass remarks and let's focus on this case." He slapped Danny on the back and his smirk grew wider. "I want this solved by sundown so I can take Catherine home and manhandle her off the clock."

Chin, who had stilled and waited to see how Steve would react to Danny's jibes, just chuckled, as Danny did the same. Chin brought up security footage from the bank so they could watch it again in an attempt to pick up on something they might have missed.

A few minutes later Steve caught the sight of the door opening out of the corner of his eye and he turned.

Although he'd only met her once, Steve recognized Kelsey immediately. He'd met her four Christmas's ago, when Catherine invited him to spend the holiday with her family, when they both had leave at the same time. It was the time her father had shown him all of Catherine's ice skating photographs and trophies. If there was one father who was proud of his daughter, it was Admiral Jason Rollins.

Kelsey looked just like Catherine when he'd met her at the Naval Academy all those years ago. She had the same eyes and the same dimples but Kelsey wore her brown hair cropped short and curly unlike Catherine who had always worn her hair long and straight.

Steve's fingers twitched as thoughts flashed in his mind of Catherine's dark silky strands wrapped around his fingers. It was his favorite way to kiss her. He'd thread his fingers in her hair and hold her captive against his mouth as he devoured her.

"Hey Kelsey, long time no see," Steve cleared his throat, shaking away those images as he greeted Catherine's younger sister.

"I'm looking for Catherine. Is she here?" Kelsey asked abruptly. Steve narrowed his eyes at her rather rude greeting. She had been polite the last time her met her but clearly something was going on as Steve noticed she was wringing her fingers tightly together.

Before he could reply Catherine walked out of Kono's office and greeted her sister with surprise.

"Kel, what are you doing here?" Catherine walked over to Kelsey and hugged her. Steve noticed Kelsey remained stiff in her embrace. "Why didn't you let me know you were coming, I would have picked you up at the airport?"

"I didn't want you to know."

Steve raised his eyebrow when Catherine glanced over at him with a confused look, surprised by Kelsey's blatant hostility. "What's going on? Do mom and dad know you're here?"

Kelsey scoffed. Mom and Dad? That's a joke."

Catherine's back stiffened. "Hey what's with the attitude? Did you get into a fight with them again or something? Is this about that biker guy you're dating?"

"How could you lie to me all this time?" Kelsey accused harshly.

Catherine's brow furrowed. "What are you talking about? Kelsey, you're not making any sense. Why don't you come in my office so we can talk?"

Kelsey reached into her bag and pulled out a piece of paper, shoving it roughly at Catherine, making her stagger slightly.

"This," Kelsey spat. "How could you lie to me about this? You of all people?"

Steve couldn't see what was on the paper Kelsey had shoved into Catherine's hands but he saw her face go white as she looked down and saw what was written on it.

"Cath?" Steve said her name when he saw her sway slightly and reached out a hand to her even though he was too far away to touch her.

"Where did you get this?" Catherine asked, her voice barely a whisper.

"That's all you have to say to me? Really?" Kelsey screeched, her tone snapping Catherine back from her shocked stupor.

Catherine's eyes narrowed. "Kelsey calm down. Come into my office." She crumpled the paper in one hand and grabbed Kelsey by the arm with the other. "Excuse us please," Catherine murmured to the trio as she led Kelsey away.

Steve watched her go, frowning.

"What was that all about?" Danny asked once Catherine closed her office door.

Steve glanced over at Danny before looking back toward Catherine's office. "I have no idea."

"Is that Catherine's sister?" Chin asked as Kono came out of her office.

"Yeah," Steve replied, distracted as he watched Catherine and Kelsey arguing inside Catherine's office. It was clearly very heated and Catherine was attempting to calm Kelsey down.

"Who was yelling out here?" Kono asked, approaching the table.

"That would be Catherine's little sister," Danny offered helpfully. "Is it wrong that I wish all our offices weren't sound proof right now?"

Chin and Kona nodded their heads in agreement as the three of them surreptitiously watched the activity in Catherine's office.

"Hey," Steve admonished, even though he was doing the same thing. He slapped his hand down on the table to get their attention. "Let's give Catherine her privacy. So what do we know for sure on this case?"

"The MO matches a string of robberies on Maui and the big island last month but these guys are pros. The never leave any prints behind and are never seen on security cameras."

"There are no plates on the getaway car," Kono added. 'But they left some tire residue on the pavement when they sped off so Fong is also running that."

The sound of glass shattering had all four of them looking over toward Catherine's office.

"What the hell?" Steve barked.

The glass wall was cracked in a spider web pattern obscuring the view into Catherine's office. The door suddenly flew open and Kelsey came running out of the office, rushing past the four of them and out the door.

"Thank goodness for safety glass," Danny said as Steve strode purposefully towards Catherine's office.

"Her sister sure knows how to make an exit," Steve heard Kono say as he stepped inside Catherine's office.

Catherine was leaning with both hands on the desk, her head hung down and her eyes shut. The piece of paper Kelsey has shoved at her was crumpled into a ball in her right hand.

The basalt lava rock paperweight that usually sat on the corner of Catherine's desk was on the floor, clearly having been the catalyst for the damage to the glass wall.

"Cath, are you alright?" Steve asked softly as he approached her.

Catherine nodded slowly. "I'm sorry about the glass. I'll pay for it."

"What happened?"

Catherine lifted her head, her eyes haunted and Steve stepped closer, reaching out grab her hand.

"Hey," he squeezed her hand gently. "What was that all about?"

Catherine shook her head but didn't speak. She just gripped his hand tighter. She looked down at the crumpled paper in her hand and then shoved it into her pocket.

"I know we have a case to finish up but I have to go after her Steve. I have to talk to her."

Steve looked at her for a long moment, wondering if she was going to answer his question. When it became obvious she wasn't, he just nodded his head. "I'll go with you."

"No," Catherine replied quickly. Steve looked at her quizzically. "I need to do this alone. She's hurt and angry and she's not going to listen if anyone else is there."

"Why is she so hurt and angry Cath? What's on that paper that's so bad?"

Catherine shook her head again and slid her eyes away from his. "Steve I can't. Not right now. I have to find her and try to fix this before I can do anything else."

Steve frowned and crouched down a little trying to get her to look him in the eye. Catherine never avoided eye contact with him and it made his gut clench that she was now. "Catherine, your sister just came into our offices, threw a fit, then a paperweight, smashing our wall then stormed out of here. I think I deserve some kind of explanation as to what's going on."

"Steve, I told you I'd pay for it." Catherine looked up at him abruptly. She pulled her hand out of his and stepped back, putting space between them as her eyes flashed angrily.

"I don't give a shit about the glass Catherine," Steve growled, frustrated. He then took a deep breath, knowing she didn't need his anger too. He reached for her hand again and lifted it against his chest. "It's you I'm worried about."

Catherine looked at him for a long moment before she sighed and stepped forward, resting her forehead against his chest. "I know. I'm sorry Steve. You deserve more than I can give you right now. But please just let me go after her. I have to make sure she's alright. I'll tell you everything tonight."

Steve wrapped his arms around her and felt her shaking. He frowned, at a loss for what to do for her. "Okay," he finally replied softly against the top of her head. "What do you need me to do?"

Catherine stepped back and grabbed a pen and paper from the top of her desk. She quickly wrote down a phone number. "Can you track her cell phone? I need to know where to start looking for her."

He nodded. "Take one of the GPS trackers with you. I'll have Chin ping her phone and send the location to you. You'll be able to track her yourself from there."

Catherine looked at him gratefully, lifting her hands and cupping his face. "Thank you," she whispered softly, tilting her face up and pulling his lips to hers, kissing him softly.

Steve pulled her tighter against him, deepening the kiss, holding her still slightly shaking body against his own. He slid his hands up her back and threaded his fingers in her hair, kissing her like he'd been thinking about earlier. Catherine's breath hitched then she sighed softly into his mouth.

After several minutes she broke the kiss and Steve rested his forehead against hers. "I have to go. She's got too much of a head start already. She knows I know how to track her and she's not going to make it easy."

"You can tell me anything, Catherine. You know that, don't you?"

She nodded. "Yes." She pulled out of his arms and grabbed her keys off her desk.

Steve followed her out of her office. Chin, Kono and Danny tried to look busy but failed miserably. Steve just shook his head and walked over to the cabinet to his right.

Catherine stopped and looked at the team. "Sorry about that." She angled her head toward her shattered office wall.

Danny shrugged. "Oh that. Please. Just another day at the office."

Catherine smiled gratefully. Steve handed Catherine one of the GPS trackers and the paper with Kelsey's phone number to Chin. "Chin, ping this number and send the location to tracker three."

"You got it."

Steve placed his hand on Catherine's waist to get her attention. She looked over at him.

"Call me if you need me."

Catherine nodded before turning and walking out of the offices.

Once she was gone, Danny asked. "Okay, so are you going to tell us what the hell that was all about?"

Steve watched Catherine disappear down the hallway, not answering Danny until she was out of sight. "I still have no idea."

"What do you mean you still have no idea?"

He turned back and scowled at Danny. "I mean I have no idea Danny. She wouldn't tell me okay."

"Is her sister always that volatile?" Kono asked curiously.

"The one other time I met her she was really sweet."

"How old is she anyway? She looks kind of young," Danny observed.

"I think she just turned twenty,' Steve answered absently. "Catherine went home last fall for her birthday."

"I remember that. It was right after Billy died, right?"

Steve nodded. "Yeah."

"Well they couldn't have more different personalities, could they?" Kono added. "I don't think I've ever seen Catherine lose her cool like that."

"She doesn't," Steve said distractedly.

"Her sister just pulled off the road near Waimanalo Beach," Chin interrupted. "I sent the coordinates to Catherine."

"Thanks Chin." Steve pulled another GPS tracker out of his pocket and typed Catherine's number into it. A map appeared on the tablet and he saw the dot indicating Catherine's phone moving along Kalanianaole Highway, just past the Hawaii Water Sports Center.

"Are you tracking Catherine?" Danny asked, already knowing the answer.

"Of course," Steve answered

"Do you think she's gonna like that?" Kono asked with a smirk.

"Do you really think she doesn't expect me to considering what just happened?" Steve retorted. Even if it made her angry with him he'd still do it. He had no idea what was going on with her and Kelsey but until he did, he was going keep her in his sights, even if it was just via GPS.

"Your funeral boss," Kono added. "Don't say I didn't warn you."

"Your concern is touching. Can we just get back to work and figure out where these robbers are going to strike next?"

Steve tried to focus on the case but he couldn't keep his eyes off the moving dot on the GPS tracker, even after it stopped at Waimanalo Beach and caught up with Kelsey.

To be continued….