Not sure why a crossover won't let you add more than one character. This is a Jack/Ianto & Dean/Cas ficlet.
Owen scowled as Ianto and Jack ran ahead of him, holding hands. "Bloody hell. Slow down, the both of you!"
Jack skidded to a stop and Ianto tumbled forward, falling on his knee. Tears welled up in his eyes. "Ow!"
Jack sat down cross-legged beside him. "You okay Yanto?"
Ianto sniffled. "I think I got an owie."
Towering over them, Owen shook his head. "See what happens when you don't listen to Uncle Owen?" He knelt down and rolled up Ianto's trouser leg. "See? No owie. Now come on, before Gwen and Tosh think I've lost you somewhere."
Ianto looked unsure but Jack kissed his knee and then helped him pull down his trouser leg. He gave him a cuddle. "It's ok, Yanto. I made it all better."
A smile lit up Ianto's face and he got to his feet. "Thanks Jackie."
Owen groaned. "Come on."
The two little boys followed their uncle Owen toward the playground, still holding hands. They broke away from their uncle and ran towards a wooden climber, laughing happily. Owen sighed, looking around for his friends. Spotting them on a bench, he headed over.
"There you are," said Gwen, giving him a gap-toothed smile. "We thought you'd forgotten."
"No, just had to deal with the little monsters."
"Owen," tutted Tosh, pursing her lips.
"So who's this, then?" he asked, ignoring her reproach.
A young man with a head full of shaggy hair held out a hand. "Sam. Nice to meet you."
Owen grunted, shaking his hand. "Which one is yours?" he asked, inclining his head toward the squealing children.
"The little brown-haired boy and the angel he's dragging around, actually," Sam replied, a smile playing at the corner of his mouth. "That's Dean and Cas. They're inseparable."
"Just like our Jack and Ianto," Gwen said, still smiling. "Can't keep them apart."
tw spn tw spn tw
Jack thrust his hand out toward the boy with the wings. "Captain Jack Harkness. This is Yanto. What're your names?"
Ianto frowned. "Jack."
"What? Just bein' friendly!"
Dean's eyes darkened. "My name is Dean." He tugged on Castiel's hand until the angel was tucked up against him. "His name is Cas, and he's my angel. You can't have him."
Jack pouted, but reached out to stroke one of Castiel's wings. Ianto's lower lip trembled and Dean's eyes narrowed. "You're kinda soft," Jack told the angel, tugging on his wing.
Dean growled. "Seriously?"
"Wanna come play on the tower with me?" asked Jack, eyes never leaving Cas.
Castiel looked at Dean, then back at Jack. "What would we be playing?"
"Fallen angel?" asked Jack, waggling his small eyebrows.
Ianto started to cry.
Dean stepped in front of Castiel. "Mine. Get your own."
Jack looked at Ianto and saw he saw crying. He put an arm around him and kissed his cheek. "Don't cry, Yanto. I was just playin'."
Ianto sniffled. "I don't have wings."
Jack shook his head. "S'okay. I like you anyways. Come on, let's go play."
Cas turned to dean, frowning. "I don't think I understand human relationships."
Dean shrugged, tugging him towards the tower. "Let's go play with them. We can teach them to play demon hunter."
Castiel's eyes widened. "'kay, Dean," he replied, trotting along behind him with his coat flapping. "But can I be a hunter this time?"