A gunman named Omar Mateen shot and killed 49 people and wounded 53 others when he opened fire inside Pulse, a gay nightclub in Orlando, on June 12, 2016.
Police shot and killed Mateen - who pledged allegiance to the Islamic State group before the carnage - after a three-hour standoff.
The bloodbath was top news around the world for days.
"Right after Pulse happened, it hit me incredibly hard," Vargas, 39, said as she strapped on wings of white fabric attached to her body with PVC tubing at a recent memorial event.
"It was offensive, it was maddening, it made me very sad."
Vargas immediately tried to donate blood, but discovered that her iron level was too low.
But her blood boiled when she learned that the Westboro Baptist Church - a tiny, vociferously anti-gay religious group - was coming to protest at the funerals of the victims.
"That was it," she said.
She was inspired by the Angel Force: volunteers wearing large angel wings who stood shoulder to shoulder at the funerals, successfully blocking the view of Westboro church members and their signs proclaiming "God hates fags".
One of the memorials at the Pulse Nightclub in Orlando, Florida. (AAP) Source: AAP
"I was like - yup, this is what I want to do to contribute to the healing," she said.
"To be the wall between love and hate."
Vargas soon joined the Angel Force, which is now an iconic Orlando group that protects lesbian, gay, bisexual and transgender community events in the city.
Vargas, a multimedia producer by profession, recently joined other Angels at a tribute to the victims at the Orlando Veterans Administration amphitheater.
This time there were no anti-gay bigots. The Angels stood silently under their heavy wings, listening to speeches and later a performance of the Orlando Gay Chorus. Its singers choked on tears between rests in the music.
"It gives me a tremendous sense of hope and peace to see them at these events," said Shannon Graves, the operations manager at the GLBT Center of Central Florida, who coordinates Angel Force activities and volunteers.
'Orlando United'
Over the past year, the Angel Force has been deployed to funerals and LGBT tribute events - and have become so ubiquitous that today they are seen as representing love and gay pride.
"The Angels are a sense of peace, and it doesn't have to be about something tragic," Graves said. "It can be something hopeful."
On Monday, the first anniversary of the massacre, Angel Force members will be present at the Pulse nightclub and at Lake Eola, where most of the tributes will be held in Orlando.
This central Florida city of 260,000 is well known as the host of vast Disney and Universal Studios amusement parks and resorts.
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For those in the know, Orlando is also widely considered one of the most gay friendly cities in the United States.
The city is already covered in signs marking the anniversary, especially banners proclaiming "Orlando United" that hang from lampposts.
At the shuttered Pulse nightclub, rainbow-printed fabric - in the colors of the Gay Pride flag - is draped over the fence, along with messages of "Love Wins".
Well-wishers have left candles, teddy bears, collars and flowers around the nightclub, which will soon become a museum.
"I will continue to be an Angel, I will continue to advocate against hate," Vargas said.
"The tolerance and the compassion here in Orlando is not going anywhere."
A powerful symbol
"What the Angel Force does is great," said Yasmin Flasterstein, who heads a counseling group in Orlando that helps Pulse massacre survivors.
"The best way to fight hate is with love, so they came with these huge angels," Flasterstein said.
"Okay, yes, there is some hatred out there, but there is so much more love."
The Angel Force idea dates to the murder of Matthew Shepard, a 21 year-old gay college student who was tortured to death in 1998 in the western state of Wyoming.
At this time the Westboro Baptist Church jumped into the headlines when it picketed Shepard's funeral.
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A friend of Shepard came up with the idea of an angel costume, complete with large wings to block the view of anti-gay demonstrators.
The angel costume idea was reborn 18 years later in Orlando, when the same anti-gay church called for demos at the funeral of Pulse victims.
"It was disgusting," Graves said, recalling the Westboro protesters.
Students at the University of Central Florida (UCF) and members of the Orlando Shakespeare Theater stepped in to design costumes - and the Angel Force was born.
Six months later the creators donated 49 of the original costumes - one for each Pulse victim - in a solemn ceremony to the LGBT Center of Central Florida.
One costume was donated to the Smithsonian National Museum of American History in Washington.
"People like us can't even wrap our minds around those kinds of things - but the Angel Force stood very strong," Graves said.
