It began as an Old Portland love story.

Fifteen years ago, on a quiet street off SE Hawthorne, Trish Grantham moved into a rental house next door to Michael Paulus—two artistic-minded exiles in search of something better. An Arizona-born high school dropout, Grantham had moved to Portland to mend a broken heart. Her ex-boyfriend was an artist, and she bought her first brush and paints to seek revenge by becoming a better painter than he was. Paulus, a formally trained artist, grew up in the suburbs of Seattle, where he tried living a drug-free “straight-edge” lifestyle at the height of the grunge era. In 1995 he came to Portland, seeking a calmer scene.

No surprise, their stories entwined.

Today, the pair collaborate on some of Portland’s most striking interiors, in a design practice centered on one-of-a-kind painted walls in residences and restaurants, including an imaginative explosion of Rorschach-style blobs in a Pearl District condo (right). Each project Grantham and Paulus tackle unites two very distinct talents, with an aesthetic that balances elegance and oddity.

Grantham calls herself an “obsessive creator” for hire. Her personal tastes lean slightly midcentury, and many of the pieces in her own home were sourced years ago at estate sales and vintage shops. She is attracted to dark, cool tones, and during color consultations she usually recommends her clients go that direction. She’s also an avid collector: an eclectic herd of antique ceramic deer line up in her living room, and vintage bird prints cover an entire dining room wall. They join works by friends and fellow artists, including one in her bedroom of Paulus’s Hello Kitty skeletons from his “Character Study” series—quasimedical, anatomical images of popular cartoons.

“She’s got her artwork, and I’ve got my artwork,” Paulus says. “They’re two totally different paths, but they come together, they bounce off each other. It’s good for both of us.”In sharp contrast to Grantham’s richly layered, playful, vintage-inspired style, Paulus seems to have little interest in décor, with the exception of a few quirky collections of his own. Turn-of-the-century French aneroid barometers, 1950s-era lenticular prints, and midcentury Japanese ceramic tchotchkes all feature in his “messy mad scientist” domestic aesthetic. When it comes to furnishings, his personal space is purely functional, totally mismatched, and “nothing like Trish’s, that’s for sure.”

A Grantham-Paulus collaboration starts with Grantham describing her vision for a space, and Paulus acting as the logistical planner and voice of reason. Once a project is vetted and approved by Paulus, he focuses on mock-ups, measurements, and preparations. Many of the rooms end up with the bold, hand-painted wall treatments that have become their signature. “They’re living things, with real texture and brush strokes,” Grantham says. “They create drama, excitement, and individuality that other homes are lacking.”

A wall is quite a jump in size from some of Grantham’s earlier canvases. In the late ’90s she was a regular at the Southeast breakfast spot Junior’s Café, where the owners loved her drawings. She would doodle on menus in exchange for meals. After some Adidas designers discovered her drawings while eating there, she was hired to do her first commercial piece.

When the two met, Paulus, who studied at Cornish College of the Arts in Seattle, became an artistic mentor for his new neighbor, teaching her the fundamentals of drawing and perspective. She reveled in their conversations about art. Over time, their friendship evolved into a romantic relationship. (They’re now back to friendship.)

As Grantham gained momentum as commercial artist, she hired Paulus as assistant, technician, consultant, and moral support. When Grantham won a commission to hand-paint a Visa billboard in New York City, the two stayed for weeks at a high-end hotel, wore custom matching jumpsuits to work, and spent many days high above the sidewalks of NYC on a boom lift.

Grantham’s first foray into interior styling also owed to serendipity. At a housewarming party (she and Paulus are no longer neighbors), a friend snapped a photo of Grantham’s kitchen. The photo made its way to Grace Bonney, founder and director of the influential interiors blog Design Sponge. Bonney asked Grantham if she could photograph her home for the site, and ultimately featured Grantham in her book Design Sponge at Home.

Around the same time Grantham was taking her first interior design jobs, Paulus was focusing his commercial work on restaurants. He painted murals for John Gorham at Tasty n Sons and Interurban, and then began to paint “wallpaper,” at spots like Angel Face and Lovely’s Fifty Fifty.

As Grantham gained confidence with her interior work, she also began to tire of the wallpaper options that were available to her clients.

“Wallpaper was getting really trendy, and I thought it looked so sad,” she says. “It looked mass-produced, there was no life in it.” She loved the look of hand-painted wallpaper but knew that most of her clients couldn’t afford the hefty price tag. Thinking of what Paulus was doing in his commercial work, and her desire to create something distinctive for her interiors, the idea of painting one-of-a-kind “wallpaper” directly onto clients’ walls was born.

For one of the first home installations they worked on together, Grantham wanted the recurring print on the walls to resemble a Rorschach inkblot. The idea appealed to Paulus’s sensibility; he was intrigued by the juxtaposition, “I like the idea of artwork that’s out of context.”

Lisa Zigarmi and Paul Del Vecchio hired Grantham to style their entire home and gave her carte blanche. They were out of town when the inkblots appeared in their foyer, and were welcomed back with walls that Zigarmi says “provide endless wonder.” A psychologist by training, she says she enjoys the presence of the inkblots: “Two years later, I’m still excited that each person we welcome into our home can find their own sense of beauty and meaning in the shapes.”

“Now that we started doing wall treatments, I want to put them in every house we do,” says Grantham.

Neither Grantham nor Paulus could have predicted that a casual friendship between neighbors would become a mentorship of sorts, then turn into love, a professional partnership, then finally a friendship that happens to produce beautiful walls.

“It’s pretty unusual, but we’re family,” says Paulus. “We are different artists, but put us together and we’re like a power artist.”