A/N: Here's chapter 4 of Baby Steps. Thanks to everyone for reviewing. Hopefully its ok! Starting to think of doing an Alpha Force Fanfiction so may start writing that soon... This part includes protective!Castle and daddy/Castle, also Baby Ryan's unofficial adoption into the Castle family. Happy Christmas and happy new year, here is my Christmas present to all of you amazing readers and especially to those of you who review and make me carry on writing this story!

Disclaimer: I don't own Castle

*previously on Baby Steps*

"The effects should wear off," A sigh of relief echoed throughout the room. "However," Kate continued, "It'll take 12 years to do so."

*Now*

"Dad?" Alexis Castle called out letting herself into the apartment. Setting down her luggage, Alexis looked round. No sign of her dad, yet the apartment was trashed. A pale blue blanket decorated with fluffy sheep around the sides lay in the middle of the destruction. Alexis frowned, why was a baby's blanket in the middle of the floor? Her dad was usually more cleaner than this. A small gurgle made her turn round to see her dad coming in the room carrying a baby. The baby was wearing what looked like a panda onesie and pale blond hair peeked out from underneath the panda baby's crystal blue eyes met her emerald ones and bashful smile emerged on his face. The baby then ducked into the crook between Castle's head and shoulder, as if shy. Richard Castle gave a deep throaty chuckle and rubbed his palm across the baby's back, "come on, bud," he tried to coax the baby out of his make-shift hiding place."It's only Alexis, she'll understand." Glancing up at his teenage daughter, Richard was surprised for her to gently say, "Hey, Detective Ryan." Detective Ryan's head peeked out of his hiding place a confused and wary look on his young face. Alexis smiled at the confusion of her dad and the pint-sized detective. "Is it ok if I call you Kevin? It'll just be to complicated to keep on calling you detective Ryan." Kevin's eyes darted between her and Castle. Castle smiled and bounced the baby on his hip."It's your choice," Castle reminded Ryan."Just because you've been turned into a baby doesn't mean that we have to make every decision for you. Even though we will be more protective of you than usual, and I definitely will as your living with me for 12 years." Kevin adopted a thoughtful expression on his face before nodding hesitantly. Opening his mouth he asked Alexis, "How'd 'ou know?" Castle nodded and added"Yea how did you know, it was Kevin?" Alexis just smiled and picked her phone out of her pocket and waved it in the air just stating, "Beckett. She thought I should know since Kevin's going to be living with us for 12 years before he can turn back." A sudden gurgle made the whole group look about. Kevin blushed a dark beetroot before he prodded Castle then rubbing his stomach saying, "Ungwe, Cas...tle" The pause in Castle's name made Alexis smile sadly at how one of New York's finest now had trouble saying anything. Castle shook his head before lightly scolding the infant, "Remember you have to call me Daddy now!" At Kevin's disgruntled face, the father and daughter laughed. "Dad, stop teasing him! Don't worry about having to call him Dad as you don't have to if you don't want to." Alexis smiled at her new baby brother. Castle suddenly tilted his head to the side a mischievous twinkle in his eyes. "Kevin," stretching his new sons name out, a Cheshire cat grin forming across his face."If you can walk to the kitchen, you can have a snack." Gently setting Kevin to the floor, a betrayed expression fluttered across the diminutive detective's face at the request. Letting Kevin's small feet adjust to the sudden pressure of his body's weight, Castle gently let go of Kevin's hands. Kevin's body shook slightly as he took a tentative step forward. He stopped stock still and trembled, trying to keep his weight evenly distributed. Lifting his foot, Kevin wobbled before falling to the right. As he lay there, blinking back tears that threatened to fall, shock coming over him. Alexis and her father ran over and bent over his shrunk form. Seeing how he shook and shivered, Castle picked him up and patted him awkwardly on the back."Hey, baby boy, don't worry I think I know how we can get you to walk..." Shooting a curious look at Castle, Kevin reluctantly gave a slight nod and agreed to go along with the plan.

*Next time on Baby Steps*

Detective Kevin Ryan learns how to walk.