"Marky sweetie!" Mark's mommy called. He glanced up from his blocks, then heaved himself onto his chubby legs and toddled to the nursery door. It was play time. Why was mommy interrupting play time? "You have a new friend over to visit," his mommy continued, coming into his room. In her arms, she held a little boy about Mark's age. Except he had lighter features than Mark. Mark frowned.

"Who dat?" Mark asked, pointing. The new boy didn't say anything, but he swatted at Mark's finger. Mark pulled his hand back. "No like," he said. "Me no like." This was his house, his mommy, and his room. Who was this boy, who just took all of that.

"Honey, this is Aaron," his mommy said, setting the boy down. He wobbled and sat down hard, staring up at Mark. Mark sat down in front of him, studying Aaron. Aaron set his hands on the ground and shoved himself onto his feet. "Aaron is younger than you are sweetie," Mark's mommy said, capturing his attention again. "I told his mommy we'd watch him tonight. Won't that be fun?"

"No," Mark said, pouting. He didn't want this boy in his house. He especially didn't want him to be there when he went over to his blocks and knocked his tower down. Aaron sat down hard and giggled, clapping his hands. "Stop that!" Mark scolded, rushing over to his tower. Aaron reached for the blocks again. "Stop it Yami," he said, because he couldn't remember the boy's name. "My blocks." He put them in the toy box. Aaron, now Yami, watched him, frowning. He liked this funny boy, but why did he take away the fun things?

"Marky, you need to share with Aaron," his mom scolded gently. "He's little. Why don't you show him your bike?" Mark brightened at that. His birthday was last week, and his mommy had gotten him a new trike. It was shiny and red and had stickers all over it. He went to the living room to retrieve it. He got on and put his feet on the pedals. But Yami and his mommy were in the living room now. Mommy had a bag slung over her shoulder, and she was holding Yami. She set him down on the ground.

"Looky mommy!" he cried gleefully, riding around the living room. Yami began toddling after his trike, laughing along with Mark. But glee soon turned to horror for the younger boy. Mark was riding a lot faster than Yami could walk, and it wasn't long before that was his downfall, quite literally. Mark turned and ran right into the younger boy, knocked him back. Yami laid there for a moment, stunned, but then tears welled in his eyes.

"Waaaaaaaa!" he wailed, scrunching up his little face and balling his fists. He was very upset. He wasn't even hurt. He hadn't hit anything. But why would the funny boy on the even funnier riding thing run into him? "Waaaa!" Mark's mommy came and scooped him up, mumbling quietly to him.

"Shhh, shhh Aaron, it's okay," she soothed. She then rounded on Mark. "Marky, why would you do that. You know you're much bigger than he is. You can't do that like you can to older cousins." Mark was very used to having his older cousins visit his house. And when they did, he could run into them with his bike. It wouldn't knock them over. "Why don't you sit on the couch while I comfort Aaron."

"Yami," Mark said stubbornly, but he did as his mommy asked. The younger boy was now calmer, but he continued to hiccup occasionally. "Sowwy," Mark apologized at last. "Sowwy Yami." He hadn't meant to make the other boy cry. After all, he'd been having fun. Yami's tears vanished as he smiled at Mark. He didn't necessarily understand that Mark apologized to him, but he sensed that the boy wouldn't do it again.

"Mawky," he babbled. "Mawky!" He laughed and clapped again. He was very proud of himself. Mark turned to his mommy, looking a little awestruck.

"He said my name mommy," he said gleefully. She smiled and set Yami on his feet. "Didn't you Yami? Huh? Yes you did, yes you did." Yami laughed and scooted away. Mark began to chase him around the living room, and when Yami tripped, he'd help him back to his feet. His mom left them be. It seemed Mark didn't mind Aaron anymore. Yami, she amended in her head. She wasn't sure how the Mark even came up with the nickname. But Yami seemed to really like it. She began dinner while also keeping an eye on the boys. Mark and Yami began rolling a ball back and forth to each other. Before too long, dinner was done.

"Mark, Aaron, dinner!" she called, serving mac and cheese and hot dogs to them. Mark climbed onto his booster seat, and his mom put Aaron in the high chair. Mark began eating, but Yami looked questioningly at his food. Mark glanced at his new friend. Why wasn't he eating? Maybe he didn't know how. Experimentally, he lifted Yami's fork, speared some mac and cheese on it, and held it in front of his face. The younger boy gobbled up the food. He was very used to having someone feed him. After all, he lived with his mommy, daddy, nana, and papa. There was always someone to feed him. "Do you know what's after dinner Marky?" his mom asked.

"Bat time!" Mark sang. He enjoyed his evening baths. He liked bubbles and his toys. "Is Yami taking a bat too?" He had to wonder. After all, his mommy always gave him a bath, let him play a little bit, and tucked him into bed.

"Do you think he should?" his mom asked. Although she'd already planned it that way. Because after that, it was going to be Yami's bed time. Mark nodded, giving Yami his fork. He demonstrated how to properly feed oneself. His mom smiled. Mark had already come a long way.

…

"What dat?" Mark asked, hovering near his mom as she got Yami dressed for bed. Yami wore diapers to bed, while Mark wore underwear. Yami didn't seem to mind. He rather liked diapers. He didn't have to get up in the middle of the night if he had to go. In fact, he didn't need to worry about it during the day either. He wore diapers during the day. She got him into his pajamas, then picked him up.

"Those are diapers sweetie," she said, carrying Yami into Mark's room. She laid him down in Mark's crib. "Aaron isn't potty trained like you are." She tucked Yami in. The young boy yawned. After dinner and a nice warm, exciting bath, he was tired. "Remember?" Mark did remember. He remembered a lot of wet pants, sheets, and blankets, because potty training was hard. "Do you want a story Marky?" she asked.

"Yes," Mark said. "Yami too." But Yami was already asleep. It was his bed time. "No," Mark amended. "Sleepy time." She shrugged. Whatever Mark wanted. She laid him down in the crib as well. Mark cuddled up to Yami, yawning. He was rather tired as well. It had been an exciting night.

…

"Well aren't they cute together," Yami's mom gushed when she came to get him in the middle of the night. "I've never seen Aaron sleep so well." Yami was cuddled up to Mark, and they were both sharing a blanket. They enjoyed it. "Come here big boy," she said, lifting Yami out of the crib. "Time to go home."

"No," Mark said, standing up in his crib. "Yami no go. He stay." Yami's mom looked at Mark's mom. She shrugged. She wasn't sure why her son was acting this way.

"Marky, Yami needs to go back to his own house now," she said. But Mark wasn't soothed.

"Yami no go!" he cried, stamping his feet. Yami began to cry as well. He didn't want to leave his new friend. He liked him.

"Mawky!" he cried, holding out his arms. His mom glanced down at him in shock. Aaron very rarely spoke, but now he wanted his new friend.

"You can come back sweetie," she said to him, turning him to face her. "How about next weekend. Maybe you can spend the whole night." Yami didn't understand. But Mark was calmer. So he wasn't worried. "Say bye-bye," she said, hoisting him up.

"Bye-bye," Yami said, waving over her shoulder. "Bye-bye Mawky."

Bye-bye Yami," Mark called. Then, satisfied Yami heard him, he settled back down for sleep.