I wanted to do this before, but one shot is ok too. 

For XMangoJuiceX

"My lord." the dark Papyrus said. He was carrying a small bundle in his arms. "I've brought your daughter." the King of Nightmares looked at him tiredly. "O... K..." "My lord, don't you want some rest? You delivered her three days ago and you spent those three days looking after her." "No... Give her to... me..." 

The little skel had his old eyes, she looked like the prince him but cuter. The little thing squealed happily and wriggled in her blanket. "Hello... Lotus..." Nightmare smiled. 

Dream always knew when something was off. Dating the flipping deadly skel Killer taught him to read his brother more. He stood before the entrance and shouted: "NIGHTMARE!!"

"Uuu... Huaaaaaaaah..." Poor Lotus began to cry. Nightmare stood up and zombie-walked to the door. He was exhausted. 

"Nightm-" Dream froze. He saw the precious little thing in his brother's arms. "Are you... babysitting?" he asked. "No... She... she's mine... my little Lotus." Nightmare looked like he could collapse onto the floor. "Brother... you look so tired..." Dream pitied him. Cross didn't go with the dark Sanses anymore. He ran away for no reason. Is... is this the reason? 

"Oh brother..." Dream looked at the smol. She stopped crying and looked up at Dream. "Aaa~" she wriggled in her blanket. Nightmare looked up at his twin. "She likes... you..." he muttered. The exhaustion of delivering and no rest caused him to collapse onto Dream. "NIGHTMARE???"

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"So... your name is Lotus. Tee hee. Sweet name." Dream carried his niece as the Healer checked over his brother. "Low energy. Some energy up items should help. But due to his exhaustion, you have to put him on liquid. Two days the least." "Thanks, Lynx." "Pfft, sure. Marey's my best friend, and you're so kind to me. I'm so grateful no way I can turn down a chance to help." the girl chuckled and left the mansion. "Lo... tus..." Dream heard his brother speak.

"I can't... I can't possibly take the-" Nightmare sighed shakily, his hands folded on his abdomen. "Nightmare." "Cross...?" the King looked up, hoping it was him. "Nightmare, I'm so sorry about that night, I was so drunk... I..." Cross faltered. "Cross..." Nightmare looked away. Could he tell? Should he tell? "Cross... I think... I think I might..." he stopped. "What? Go on." "I... I think I'm with child." 

Blood.

Blood everywhere. 

"Cross...? Why..."

"Marey..." Nightmare looked up. 

"Lynx? Why..."

"Mu-mummy... Help her..." a timid voice whined. 

"Tussy? Cross, what are you doing? That's our daughter!" 

"Correction: That's YOUR daughter. I'm not taking such burdens."

"Marey, take your daughter and go..." Lynx warned.

"Lotus? Where are you?" 

"MUMMY!!!" Cross' eyes glowed and he slashed his own daughter with his knife.

"LOTUS!!!" Nightmare jumped up and looked around, flipping scared. "Waaaaaaaa..." "Oh, no, shh... shh..." Dream tried to calm his niece. Nightmare looked at the two, tears adorning his face. "Oh, my stars..." he sobbed. "What is it, Nightmare?" "Nothing..." Nightmare hugged himself. He muttered "An irresponsible father." 

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"Ma... mi..." Lotus called. She was 4 months now. "Nightmare! Lotus said her first word!" "Hmm?" Nightmare came out, the dark Papyrus following him. "Ma... mi...?" Dream squealed. "She just called you mommy!!" 

Nightmare blushed and watched his little girl play with her uncle. He wasn't going to let anyone hurt her. "My lord? Someone's at the door." "?" Nightmare went to check.

"Marey!" Lynx giggled, throwing herself onto him. "Haha! Cat!" he let her hug him. "Look who I found!" she looked behind. The punky skel blushed and looked down. "Nightmare..." 

"Cross..." his grip tightened. He remembered his dream, he slashed Lotus, and he hurt his best friend. "Why are you here?" 

"I came to see her. I want to see our Lotus." 

He wants to see Lotus?

"Are... you kidding...?" he was in a whirr. 

"Please, I'm sorry I left you for so long. I'm sorry I was never there for you both. Please, at least let me meet her." Cross pleaded. Nightmare sighed, what could he do.

"Hee...?" Lotus looked at the new person, curious. "H-hey, Lotus. This is Daddy." Cross cooed. "A...dee...?" she babbled. Close. 

"Yeah, this is Daddy." he tried to pick her up, but Dream refused. "You broke my brother, you chocoholic!" he fumed. "Dream..." "Brother, let him. He... I know when sorry is sorry." Nightmare pleaded. Dream, though shocked, reluctantly gave her to him. 

"A...dee!" Lotus laughed. Cross blushed and kissed her forehead. "Yeah, from now on, it's you, me and Mommy."