She took her first trip as an adult in August, going to Cuba on a week-long vacation with friends. A long-term relationship with her boyfriend, Nick, was going well.
She had graduated from St. Pius X Comprehensive High School two years ago and spent the following year working for a telemarketing company while taking math courses at night. She suffered from dyslexia, but worked hard to improve her grades.
This month, she began studying international business at Dawson. "She was loving it," said her aunt, Natalya Hevey. "She was enrolling in intensive courses. She loved everything about it."
Family and friends searched in vain for eight hours Wednesday, staking out Dawson and various hospitals. They called hotlines, the police, her friends and her cellphone.
Finally, at 9:30 p.m., police confirmed the news they had prayed they wouldn't hear.
Twenty people were wounded in Kimveer Gill's rampage Wednesday. DeSousa was the one he killed.
"It's the end of everything for her," Hevey said, passing the teen's graduation photo to a Gazette photographer.
"I want the world to see what a beautiful person she was."
In the home of DeSousa's grandparents in Ahuntsic, photographs of children and grandchildren cover the walls of the rooms and corridors.
Snapshots share space with professional studio images.
Intermingled is a poem DeSousa wrote for her Polish grandmother for Christmas, titled My Babcia (a Polish term for grandmother), in which she writes:
"Always here for me when I'm sick /Always here for me when I want to stay home from school ... / The coolest, most hip grandmother in the world / My Babcia."
Family was their art. Family was everything.
DeSousa's father, Nelson, an auto mechanic who works for Honda, described her as "a bottle of champagne, filled to the rim, ready to explode. She was always the centre of attention."
Her mother, Louise, said yesterday her daughter "loved to party, to go out on the weekend and enjoy herself."
"She was the one who got a party going," she said, holding a picture of her daughter taken before her high school prom.
In the photo, the attractive, petite blonde is wearing a pink dress and is surrounded by a group of handsome young men.
"She had guys lining up behind her, she had an entourage," Louise DeSousa said.
Her sister, Sarah, 16, said DeSousa loved going to nightclubs and dancing to hip-hop, reggae and salsa.
The teenager's room was painted bright pink and most of her clothes were pink, too.
"When you open her drawers, all you see is pink," said Sarah. The family joked that the 18-year-old's colour preference was a holdover from playing with Barbie dolls as a child.
"We were best friends," Sarah said.
Nick DeSousa, 11, said he would remember his big sister as someone who "would always take me places," like out to lunch at McDonalds or to buy video games.
On the morning of the shootings, Louise De Sousa went into her sleeping daughter's pink bedroom and kissed her on the cheek before leaving for the day.
The teen spent half an hour at home, working on an English paper, then rushed off to take the metro to school. Although she got her driver's licence last year, she usually took public transit to get downtown.
Her father remembers smelling her perfume after she left.
"She was our princess," said her aunt, Hevey. "She was our Juliet.
Her cousin, Priscilla Rivas, 11, said DeSousa has been extremely supportive as she tried to overcome dyslexia, the learning disability the two shared. "She told me I had to be strong."
Louise DeSousa said that her daughter worked hard. "It was always a struggle for her," her mother said. "But she had extremely big goals. One day, she wanted to own her own business."
In her graduation write-up in her high-school yearbook, De-Sousa finished with a final thought for her classmates.
"Good luck in life!"
DeSousa attended several different high schools - Villa Maria from Grades 7 through 9, then Royal Vale and St. Pius X Comprehensive High School. Even so, the friendly teenager clearly wasn't a student who slipped under the radar screen.
Students at Royal Vale in Notre Dame de Grace yesterday created a memorial to DeSousa, who went there for Grade 10 in 2003-04.
They placed an old yearbook on a table and opened it to a picture of DeSousa. They also bought a pink rose for the tribute - a nod to DeSousa's penchant for wearing a dash of pink to liven up the school's grey and white dress code.
"They remember her as the girl who loved pink," principal John Roumeliotis said.
"That was her trademark."
The students also plan to honour DeSousa - and the other victims from the Dawson College shooting - with "free dress day" next Wednesday, he said.
Uniforms are out that day, but the colour pink will be de rigueur.
The students intend to raise money for the Montreal Children's Hospital that day, Roumeliotis said.
DeSousa, who had a Portuguese background and lived in Laval, attended Terry Fox Elementary School - where brother Nick is now a student. Yesterday, the flags flew at half-mast and grief counselling was being offered at the school.
Frank Di Paolo, her former principal at St. Pius X, had to pull over yesterday on a street when he realized DeSousa was the slain 18-year-old.
"She was involved in all aspects of school life," said Di Paolo, now the director of the John F. Kennedy Business Centre.
"She was a bright and beautiful young lady. Full of life - always had a smile on her face."