Authors Note; This is a challenge suggestion from Caskettfanoz, who wanted to read a story that had to do with an early budding relationship with Caskett, and Kate get's scared of the idea of an 'instant family'. Doesn't want Alexis to think she's trying to replace her mom; But Alexis has a talk with her and explains why Kate is more of a motherly figure to her than Meredith or Gina. This is technically my second Castle fic, but we'll call it my first.

Summary; Kate starts to get cold feet about her new little family and worries about what Martha and Alexis think, mainly Alexis, not wanting to replace her mom. Alexis has a serious talk with her about why Kate is more of a mom than Meredith was/is. Will Kate decide to risk her heart?

Disclaimer; The Easter Bunny was mean and didn't bring me Castle. :C So they don't belong to me.

Your Heart May Be On The Left, But It's Always Right

Chapter One

Bleeding Love

"I can't do this, Castle! I just-c-can't." Kate Beckett pushed away from her boyfriend, attempting to extract her forearms from his grasp. Tears were threatening to break free as she turned her head to the side to avoid his stare. Richard Castle and Kate Beckett had finally broke unspoken rules, crossed that invisible line; Finally, they had decided to give each other a try. But they hadn't been together for very long. 3 months ago, on this particular day...Blue eyes met green, heart rates quickened and the space was closed as lips met in a passionate and longing kiss.

Castle stared at the woman before him, a surprised and very hurt expression on his face. "W-What? Kate. You can't-You can't-" He stumbled on his words as Kate managed to break free of his grasp.

"You can't just ask me to move in with you!" She stared at him with a terrified expression on her face, slowly and absently backing toward the door. Rick gently grabbed her arm once more, confusion etched all over his face.

"Why not, Kate? Why can't I? I love you, and I know you love me. I know you do." His voice was pleading as was his expression. His normally bright blue eyes were now a stormy gray as they silently begged Kate to stay.

Kate closed her eyes, quickly bringing a hand up to meet her cheek as she brushed away a stray tear. Swallowing the lump in her throat she took a ragged breath and brought her gaze back to meet Castle's. "I-I'm scared." her voice was barely audible.

A shadow formed at the top of the stairs as Alexis Castle moved with skill to keep her presence un-known. She was struggling to hear the conversation now. She had been in her room, attempting homework when she heard the sudden outbursts. Her heart fluttered inside her chest like a trapped bird. She couldn't believe what she was hearing. Alexis had watched her father and the beautiful Detective Beckett dance around each other for almost 3 years now and they had finally got together. She had been ecstatic. Kate Beckett was perfect for her father, they were like Yin and Yang - They balanced each other out. Castle kept Kate from getting too serious and helped her relax while Kate helped Castle do just the opposite. They couldn't be fighting about something like this. Kate kept trying to go for the door and the closer she got the more Alexis's heart dropped. She strained to hear the woman as she fought her emotions to speak.

"Scared?" Castle repeated. "Of what?" He forced her into a hug. Kate stiffened her body against his, forearms resting against his chest and head turned to the side.

"All of this." Kate mumbled into his chest. "I-It's too much, Castle." She pulled her head back to search his face and eyes.

Castle did the same, refusing to let go of her for fear that she might leave. "O-okay. I'm sorry I asked, Kate. I know I can be a little eccentric. I just thou-" He was cut off as Kate shook her head.

"Not just of you asking me to move in," She paused, visibly swallowing. "it's Alexis and Martha...I-I've just been on my own and-It's like-An instant family. I mean...Don't get me wrong. I love them both. Alexis is amazing and sometimes I forget she isn't biologically mine." She chuckled softly at the thought and shook her head. "I don't want to invade in their personal space and I certainly don't want Alexis to think I'm trying to replace her mother." She sighed and her lower lip caught between her teeth.

Castle gave her a very reassuring smile. "Kate, you wouldn't be 'invading' their space, you'd be sharing it. You shouldn't worry about such things. Alexis adores you, as does my mother. Alexis is smart enough and mature enough to know you aren't trying to replace her mother just be her friend." His voice was soft and he kept his grip around her as he rubbed her back softly.

"I-I just-I need to think, Castle." Kate looked up at him with a sad smile and reluctantly pulled out of his embrace, but not before letting her lips linger and hover over his, as if debating on weather she even wanted to kiss him. After a couple of second, she allowed their lips to touch but a little too short for both their liking.

Alexis was completely shocked at Kate's words. She didn't think Kate was trying to replace her mother or 'invading her space', whatever that meant. She figured it was some sort of excuse. Alexis believed that the woman was scared, yes but she believed that Kate was just using those as poor excuses. Even if Kate wasn't trying to replace her mother, Alexis considered her more of a motherly figure than her own. The strawberry blond teenager watched as the woman who bother her father and she cared for, walked out the door. Alexis could see the horrified look on her father's face and she imagined that the look on her face was similar. There was no way she was going to let this happen. It was time to take matters into her own hands.

Kate lay on her couch, her knees to her chest as she stared off into space. She had been perfectly content with the way things are. Why did Castle have to go and ask her such a serious question. If she moved in with him, that would mean things were serious. Not that they weren't now, but if she moved in, that would mean seeing both Castle and Alexis everyday. If, God forbid Kate and Castle had to break up, it would devastate her. She'd be so used to being with them...Alexis, what if she didn't approve of her? Kate shook her head at the thought. Alexis loved her. She knew this, why was she being so stupid?

.-.-.

Her thoughts were short lived as a knock at the door sounded. Oh, God. What if it's Castle? I told him I needed time to think! Kate thought, as she got up slowly and meandered to the door. Her hand touched the door knob and she paused. Another knock.

"Kate? It's Alexis." Came the muffled voice of the Castle she was most certainly not expecting. She opened the door, revealing a serious faced Alexis.

"A-Alexis, what are you doing here?" Kate stammered as she held the door open for Alexis to enter. The teenager shuffled past Kate and then turned to watch her close the door.

"I need to talk to you, Kate."

Kate nodded toward the couch. "Okay...Uhm, let's take a seat, then." She mumbled as she herself walked to the couch and took a seat.

Alexis shook her head. "I prefer to stand if it's alright with you." She waited for Kate to nod before she started to talk. Kate looked nervous as she noted the serious expression on Alexis's features, as she placed her hands on her hips. Her eyes were a deeper blue, Kate thought.

"Look Kate, I heard you and dad fighting." Alexis waited to gauge Kate's reaction before continuing. Kate's eyes widened and visibly paled. She opened her mouth to speak, but Alexis beat her to it. "I'm not done, Kate. Before you speak, I'd like to voice my opinion first, I think I have a right." She eyed Kate carefully as she nodded.

"O-Okay." Kate agreed.

"Thank you." Alexis paused, taking her time to gather her thoughts. "Alright, Kate. You are crazy." Kate's brows knitted together in confusion. Did she come all this way just question her sanity? "I know the reason you're scared of moving in isn't because you don't want to -she used air quotes- 'invade our space', it's because there's a lot to lose. You'd rather not risk your heart." Alexis's tone softened as her hands dropped to her sides.

Kate stared at the smaller Castle, shell shocked at her words. "But aren't we worth the risk, Kate? Don't you love us? I know you do. You treat me like I'm you're daughter, make an effort to spend time with me, talk to me. I know you say you don't want to replace my mother, but honestly there is nothing to replace. I love Meredith, but she's never been a motherly figure to me. There's a reason I don't really call her 'mom'." Alexis stated, searching Kate's features.

She continued, "You have been more of a mother to me than Meredith and Gina combined. Gina didn't even try, really. I don't know what dad was thinking. You know all to well, that I think you and my dad are great together, and I have no problems what so ever. As for Grams, she loves you; Thinks you're great for dad. So you can't use us as excuses. I know the real reason you're scared. You can't keep running Kate. And you can't leave us." her voice began to tremble now and she strained to steady it and continue. "Y-You can't leave me." Kate immediately noticed the tears threatening to break free.

"Lex..." Kate's voice was soft as she spoke. She stood up and moved to wrap her arms around the young teenager in a bone crushing hug as she broke down. "You're right. I'm scared to lose you, and your dad, and Martha. You are worth the risk, Lex. I'm sorry." Kate softly ran her fingers through Alexis's hair as the young girl cried into Kate's shoulder.

After a couple of moments, Alexis regained her composure and forced herself from Kate's embrace to search her face. "Don't be scared of us, Kate. We love you, I love you. You're the mother I never had. You might as well be my real mom. So-" She looked down, and the serious expression that had adorned her face earlier was replaced by a shy little girl-like expression. "Stay, please stay, and be the mom I never had...That is if you'd want to be." She could feel the heat rise up from her neck and dance across her cheeks.

Kate's breath caught in her throat and hear heart flipped at Alexis's words. She opened and closed her mouth like a fish, unable to find her voice. Alexis mistook this as Kate not wanting to be that sort of role to her. She backed away, hurt clearly evident on her young face. She couldn't fight back the tears that started to fall. Seeing this, Kate immediately regained her voice.

"Alexis, I-I-don't. Come back here." Kate reached out and pulled Alexis back into her embrace, kissing the top of her head. "I'd be honored. I already think of you as my own, I promise, no matter what...You'll always have me." She lifted Alexis's chin and smiled down at her.

"R-really?" Alexis gave a teary smile. Kate nodded, moving them both toward the couch and plopping down on it, pulling Alexis down with her.

"Even if your father and I-" She faltered, and Alexis nodded, knowing what she meant. "Even if that, you can always count on me." She pulled the girl into her side and hugged her close.

Alexis smiled a looked up at Kate. "Would you uhm-" She bit her lip and blushed. "Would you mind if-I-If..."

"If what, Lex?" Kate's brows furrowed as she nodded for the girl to continue.

"IfICalledYouMom." It all came out so fast, Kate wasn't sure she heard her right. To say she was shocked as an understatement.

"Huh?" her mouth hung open, and her eyes were wide.

"I-I asked if-You know what, never mind, it's stupid." Alexis blushed and sat up straight against the couch.

Kate shook her head. "No, No. It's not stupid." she herself blushed. "I-I was just surprised. I don't think I deserve such a title..." As she looked away, Alexis scooted back closer and smiled warmly.

"Oh but you do, you're just...Amazing." She finally said.

Kate smiled and looked back at the teen shyly. "I-I wouldn't mind that, if you're sure you're comfortable with it." Alexis nodded emphatically.

"I am...Mom." The word rolled off her tongue, and it felt...right. Kate's heart practically leapt from her chest at the term. Her smile grew wider and she couldn't help but hug Alexis tighter than before. "I guess that means you're really okay with it." Alexis chocked, as Kate squeezed the air out of her. The older woman quickly let go and blushed.

"Sorry." She smiled shyly and Alexis laughed.

"It's okay."

They sat in silence for a moment before Kate broke it. "So, should we go...home?" That word felt right. Home. Alexis beamed and nodded.

"We shall." She said, grinning.