A/N: Fun fact, I had written this story before but I had lost it a long time ago. So since I was requested to do a Kiddlaw. I figured this would be the perfect story.
Haha, well, enjoy Kiddlaw.

Kidd yawned coming home from work and shutting the door. He sighed as his amber glance caught a tuft of blonde haired baby. He stiffened before slamming back into the front door. The boy turned to him chewing on his fist. Drool glistening off his fist and dripping down onto the floor. The boy smiled before pulling his fist out of his mouth.
"LAW!" Kidd called.
Law shut his book before heading to the front door where Kidd was pinned to the door by the baby crawling closer to him. Law chuckled approaching the boy and picking him up. The boy had an unbroken stare with Kidd. Law put a binky in his mouth before wiping his slobber off his fist and mouth.
"What is that?!" Kidd asked.
Law turned to Kidd putting the rag in his pocket.
"It's a baby Kidd, this is Satori-ya we're babysitting while the Roronoa-ya family goes out for a date and will pick him up tomorrow morning." Law explained.
Satori squealed with laughter before holding out his hands to Kidd.
"He wants you to hold him." Law said.
"Oh no. I'm not holding. That." Kidd said.
Satori laughed again still holding out his arms. Kidd pursed his lips in a line as Satori's baby eyed look was getting to him. He pressed his lips harder before he growled and took the small being from Law. He held him out in arms length as Satori smiled wiggling in his grip.
"What!" Kidd barked.
"Hold him closer." Law said leaning against the wall.
Kidd turned to Law smirking with his legs and arms crossed. He squinted to him.
"Your enjoying this aren't you?" Kidd growled.
"Very yes."
Kidd turned back to the boy who was holding out his arms again. He sighed rolling his eyes and holding Satori closer to him. He smiled putting his tiny hands on his cheeks. Kid cracked a small, very faint, smile. Law witnessed it for a second before he frowned and set the boy down.
"Okay now leave me alone." Kidd said.
He went upstairs as Satori soon followed him up the stairs crawling. Law watched the boy as he made it up to the top of the stairs. He turned to Law and gave a thumbs up. Law chuckled.
"Yes good job Satori, you have fun playing with Kidd okay?" Law said.
Satori nodded before crawling into there room. Kidd pulled on his sweatpants and wiped off his makeup then pulled up his wet hair into a bun before heading out of the bathroom. He screamed and staggered back when he saw Satori standing in front of the door. He stood sucking on his binky and reached up to Kidd.
"Look kid I'm not picking you up again."
Satori sniffed as his eyes started to water, Kidd started to panic as Satori started to cry. He knelt down to him and scooped him up. Satori stopped crying and looked up at him and smiled. Kidd smirked wiping away his fake tears.
"You little fake, I thought you were really crying." Kidd chuckled.
Satori chuckled as Kidd stood up holding him. Kidd pinched his cheek as the boy laughed in his arm.
"I guess you aren't so bad." Kidd smirked.
He went downstairs as Law perked up from opening a small container Sanji made for Satori to eat.
"Well it looks like you made a new friend." Law said.
"Shut up." Kidd grunted.
He chuckled as Law pulled out the little plastic spoon and set it on the counter. He turned to Kidd making faces at Satori.
"So. You gonna feed him too?" Law asked.
Kidd turned to Law with his lips pursed before he scowled.
"Tch, no."
Kidd set him in his little high chair before he went to the living room. Satori watched him walk away before turning to Law.
"Re-re." He pointed to Kidd.
"Re re?" Law cocked a brow.
Satori patted his head, Law chuckled.
"Red? Is that his name?" Law asked.
Satori smiled and nodded.
"Re-Re! Ooo!"
Law chuckled, "You'll see him after I feed you okay?"
He stirred up the baby dinner for Satori before feeding him the mashed carrots. Law mimicked Satori's chewing method making sure he ate it all. Kidd watched from the living room and smirked to Law's faces he made. He pushed off the wall and headed to the living room where Satori had knocked over his toy box and a few toys were spread across the floor. He smirked as Satori came rushing in and stood in the doorway.
"Hey champ." Kidd smirked sitting on the couch.
Satori smiled rushing over to him and tripped. Kidd got up and went up to him and helped him up. Satori looked up at him with watery eyes. Kidd awed him and pulled him close.
"It's alright buddy look your fine." Kidd said.
Satori sniffled sticking out his bottom lip.
"See look, there's this little piggy."
He tugged slightly on his toes having the boy smile and giggle. Before he was bursting with laughter as Kidd played little piggies. Law sat on the couch as Kidd and Satori sat playing with his toys. Satori sat on Kidd's lap resting against his forearm and. Fell asleep.
"Law." Kidd whispered.
He perked up as Kidd smiled pointing to the boy.
"He fell asleep." Kidd grinned.
Law chuckled, "I guess you wore the poor boy out."
"What do I do?" Kidd asked.
Law got up and knelt down before them. He scooped up Satori before kissing Kdd softly.
"I'm glad you had fun." Law hummed pulling back.
"I didn't. I was. Entertaining him."
Law smirked, "Whatever you call it Eustass-ya."
Kidd pursed his lips as Law got up and started to head up the stairs.
"H-Hey where you going to put him?" Kidd asked.
"In the office of course. They let us borrow a cradle. I set it up earlier for his nap."
"Why don't you just put him in our room in case something happens? Or he needs me?"
Law grinned, "Needs you?
Kidd grunted, "You know what I mean."
He chuckled, "He will be fine Kidd. It's not like your growing attached to him are you?"
"Tch of course not."
Kidd turned away having Law chuckle and go upstairs and open the door to the office. Law set Satori in his crib and tuck him in. Kidd crept in and peaked over Law's shoulder. Law glanced to him and smiled softly. Law smiled resting against his shoulder.
"Hey law." Kidd muttered.
"Yes dear." Law whispered.
"I want one."
Law turned to Kidd, his amber eyes burrowing into his grey.
"You want a kid?" Law asked.
"I mean why not, we're not getting any younger and then our kid can play with their kid and-"
"Slow down Eustass-ya." Law stopped him.
He nudged him out of the room to the hallway. Law shut the door and turned to Kidd.
"We're not even married. Hell Kidd we've been dating for only six months."  Law said.
"So what! Like I said we aren't getting any younger. Let's get married Law. And spend the rest of our lives together." Kidd grinned taking Laws hands.
Law sighed and shook his head, "Alright, fine. But I expect you to go all out for my proposal."
"You want more?"
Law chuckled, "I did live under Doflamingo for a long time. Until he agreed for me to live with you. Maybe if-" Law pulled a toothy grin.
"Alright. I'll marry you if you ask Doflamingo for his permission for you to marry me."
Kidd groaned, "Your kidding."
Law smiled walking to the bedroom, "Yep. Thats how you can prove to me your serious about this."
Kidd pursed his lips and followed Law, he watched Law strip of his shirt and jeans before crawling into bed. He turned to Kidd with a slight hint of blush.
"You do that every night." Law huffed.
Kidd chuckled shutting off the hallway light and going into their room.
"What?" Kidd asked.
"You stand in the doorway and watch me strip." Law said.
"I figure that's why you do it. For me to watch over your bare form."
Kidd crawled into bed and pulled Law close to him. Law reached over turning out the light. He tossed over to Kidd and ran a finger down his lips. His breath warm on his cheek. His hand trailed up to his cheek and kissed him.
"I hope your serious about. What you said earlier." Law said.
Kidd hummed as they snuggled close and fell asleep. The next morning Law woke up to a slight tapping. He groaned opening his eye to Satori patting Kidd's forehead. Law smiled resting on his elbow. Kidd groaned batting away his hand. Law chuckled as Kidd was still asleep and scratched his neck. Law reached over and patted Satori's head. The boy noticed Kidd's mouth open as his little fingers made its way past his lips. Kidd snapped his eyes open as Law and Satori laughed. Kidd pulled his hand out of his mouth and sat up.
"How did you get in here you little stinker." Kidd chuckled picking up the boy.
"Satori is an escape artist. I'm surprised he's still in his pajamas. Sanji-ya warned me he can escape his crib, onesies, and his own booster seat." Law said.
Kidd smirked, "Look at you."
Satori laughed as the doorbell rang.
"Ada. Dadda." Satori muttered.
The boy climbed out of bed and raced out of the room. Law followed behind as Kidd was left alone. He pursed his lips following the others. He headed down to find Satori in Sanji's arms. Kidd was heartbroken. Satori was all bubbly and giggly in his arms.
"I hope he wasn't too much for you guys to handle." Sanji said.
Zoro rolled his neck crossing his arms.
"Not at all, we really enjoyed having him here. He became good friends with Kidd." Law said.
Sanji smiled, "So you guys wouldn't mind if you babysat him again?"
"Not at all." Kidd blurted out.
"Wonderful." Sanji chuckled.
Zoro and Sanji helped clean up. While Kidd said his final goodbyes to Satori.
"Well little guy. Imma miss you. I'd tell you to keep out of trouble but you already are." Kidd said.
Satori got up and hugged Kidd's neck. He pulled back and smiled.
"Ed-ed." He said.
"Come on Satori. It's time to go home." Sanji said.
"Ada!" He cried.
Satori wobbled up to his father who scooped him up.
"Thank you again for taking care of him." Sanji said.
"Anytime." Kidd said.
The couple left along with the child leaving Kid and Law alone. He sighed resting back against the couch. Law walked into the living room holding coffee. Kidd seemed to be spaced out. As Law sat next to him.
"Hey." Law said.
Kidd turned to him, and took his coffee.
"I have to go to work soon." Law said.
"Hmm." Kidd hummed.
Law sighed leaning over and kissing his cheek before getting up and going upstairs. He drank some of his coffee before dressing himself in his scrubs and his coat and then into his work shoes. He stepped out taking his mug. He headed downstairs to find Kidd's cup sitting on the floor.
"Kidd!" Law called.
But no answer. Law sighed leaving for work. He noticed Kidd's car missing but he brushed it off thinking maybe he had to go to work early too. Law arrived at work and his two nurses greeted him at the door.
"Doctor." They both greeted.
Law nodded as they followed him into the hospital.
"Sir, we have a man who needs stitches. And a woman who needs a check up." Penguin said.
"Law!"
He turned to Kidd bursting through the door, he was panting. His hair a tangled mess and sweaty.
"Go get some water now." Law spat."
Penguin and Shachi ran off as Law approached Kidd. He stood up straight and took a breath before handing him a piece of paper.
"What's this?"
"You said if I was serious. Just read it."
Law took the paper and unfolded it.
'I Donquixote Doflamingo grant Eustass Kidd permission to marry my 'son' Trafalgar Law.
Signed Donquixote Doflamingo.'
Law looked up to Kidd, "Your serious about this?"
"I got it in writing. In case you didn't believe me."
Law looked at the paper again before looking at Kidd. He walked up to him and embraced him.
"Alright. Let's go through with this." Law sighed.