“A huge part of what I do is about growing up and still keeping that kid side of you,” Sokoler says. “So many people grow up, and they’re always stressed and working, and everything is serious from then on, and I think that’s very sickening. You can still keep this fun side of you, the side of you that enjoys making cupcake sandwiches for breakfast. I think people forget how to have fun when they’re older.”

In the spirit of keeping the kid in her alive, she also engaged in a shadow project, appropriately inspired by Peter Pan. She traced and cut out life-size silhouette “shadows,” taped them to walls and sidewalks, resumed her secret-agent squat, and discovered an elderly man’s shadow break- dancing and a girl’s shadow holding flowers next to a graffitied door. She pasted paper eyes to trees and parking meters, photographed hearts flowing out of rusty pipes, and introduced some Tinkerbell-size neighbors (photo cutouts of herself and her boyfriend, Matty) to fix the street’s tiny problems.

And then she blogged about it. Through her bubbly, feel-good blog, ColorMeKatie.blogspot.com, which is a virtual gust of colors and optimism, her art reaches thousands of readers residing everywhere from Germany to Australia and creates a stronger sense of community in her neighborhood of Greenpoint. Once, at a bus stop, she pasted a thought bubble with an image of her flying, and the next day, she found a myriad of local blogs discussing the bubble and posting their own pictures of it. One photo even managed to capture a woman with a broken leg and a cane under the bubble.

“It was perfect for it, because someone [who] can’t really walk at the moment would daydream about flying,” Sokoler says.

She stirred up excitement in her neighborhood when she featured photos of local shopkeepers on her blog. She even knows most of the area dog owners due to the time she spends at the dog park (she has no dogs, only an acrobatic cat, Moo). She’s finding the community she always wanted — but never had while growing up — in a vast metropolis, where it is polite to ignore and where sidewalks are a main focal point. She’s also making Gotham look a little more like Sesame Street.

But often, people don’t notice.

“That’s the saddest part to me,” Sokoler says. “They walk by, and so many New Yorkers just look down and don’t pay attention. People block themselves out, and everyone thinks each other is dangerous. There’s reason to be afraid. There are bad people out there, but not everyone is.”

Her own thought bubble is only getting bigger. She envisions involving more people in her creativity, maybe even using social-networking sites to incorporate her blog followers, and she’s also in the process of making a book about her street art. She wants to give the world a splash of color, a splash of Katie.

“It seems like my website is a kind of escape [for my readers] from their world,” Sokoler says. “It’s like an escape for me too. Even when I’m having a bad day, I’ll go to my website and look at the little things and be like, ‘Ah, okay, that makes me feel better.’ ”

Sokoler continues to chase the shadow of her childhood and pull passersby out of their mundane routines and into unexpected fairy tales. She’s capturing and giving life to the secret fantasies of Laundromat owners and retirees. To her, their fantasies are as real and as silly as her own.

“My shadow would be off the ground, flying away with balloons or maybe a kite taking off. Something very magical,” Sokoler says. “My thought bubble? It would just be full of lots of love.”

Still, Sokoler is on a mission to make the city smile. She’s learned that even though her art is right in front of people’s noses, many folks are programmed to walk by with a 40-degree stare, especially in a place like New York City.

“I have a plan for that,” she says. “I’m going to put art on the floors.”