When You WIsh Upon a Dragon by lupins - http://archiveofourown.org/works/815856
Stiles is at the Hale house, lounging on the front stoop watching Isaac, Erica, and Boyd wrestle, when the baby comes running out of the woods.Derek becomes instant father to a magically appearing baby and falls in love. Stiles can’t take the cute and worries Derek’s heart will break if he loses the kid.
Lord Knows It Would Be the First time by Uraneia- http://archiveofourown.org/works/778759?v
Summary: Stiles is home from Berkeley for the summer, but only because he promised the pack. He'd rather not see Derek, because whatever the thing was that they were doing, they're not doing it anymore, and it sucks, Unfortunately, he doesn't have a choice. The betas tried a magical remedy for Derek's melancholy, and now Stiles has a three-year-old who looks like Derek. Stiles doesn't know how to deal with that, and hedefinitely doesn't know how to tell the betas he and Derek were secret fuck buddies for a year and a half.
Title: True Love’s Kiss
Fandom: Teen Wolf (2011)
Pairing: Derek/Stiles (Peter/Chris)
Length: 8,973 words
Spoilers: Through season two.
Summary: “Oh, you know,” Lydia said. “The usual. A witch, a spell, and voila! Puppies.”