Amid a low key official ceremony to mark the 10th anniversary of the deadly Lindt Cafe siege, Louisa Hope quietly placed flowers outside the former eatery where she was held hostage for almost 17 hours.
It's a private ritual she has performed every year since.
"It's something that does not go away," she said.
"One of my fellow hostages said to me that, every morning when he wakes up and every night before he goes to bed, he thinks about the Lindt Cafe."
Ms Hope was one of 18 people, including her mother, taken hostage by Man Haron Monis after he entered the cafe on Sydney's Martin Place on December 15, 2014.
At gunpoint, he forced hostages to call police and media organisations, falsely warning that he was carrying a bomb and had placed other explosives around the city in an attack by Islamic State.
A dozen people managed to escape during the 16-and-a-half-hour siege before police stormed the building and ended the tense stand-off.
Two of the hostages were killed: cafe director Tori Johnson, who was executed by Monis at 2.13am, and barrister Katrina Dawson, who was fatally injured by fragments from police bullets.
Prime Minister Anthony Albanese laid flowers in Martin Place on Monday alongside state and federal leaders and Ms Dawson's parents.
The decision to hold a muted memorial without speeches or grandeur came after discussions with the hostages and their families.
"It was a terrible event that traumatised this city," Mr Albanese said.
One of the officers who breached the cafe to end the siege has spoken of his trauma and struggles. (Dan Himbrechts/AAP PHOTOS)
NSW Premier Chris Minns said there was no right or wrong way of marking the day as he offered support for a national probe into first responders' trauma.
The inquiry is the brainchild of Ben Besant, a former tactical operations unit officer who stormed the cafe and killed Monis.
Now working as a carpenter, he wants more Australians to speak up about PTSD.
"Within police officers and first responders and military, we're quite stubborn and not willing to talk about our feelings ... my message would be, you can't do it by yourself," Mr Besant told AAP.
"Take the plunge, apply yourself to a fight, you have to fight to beat PTSD."
Mr Besant, who could only recently be named publicly after a suppression order forced him to be referred to as "Officer A", said he faced many things over two decades in the police force.
"But for me, Lindt (Cafe) was always the one that I couldn't deal with," he said.
To this day, he cannot properly process finding Ms Dawson, her dying in his arms and later discovering her injuries were caused by fragments of police bullets.
"I've always blamed myself for that," he said.
Ms Hope, who has found a remarkable friendship with Mr Besant, said she had also battled PTSD, including what she describes as "excruciatingly violent" random thoughts that came out of nowhere.
"I was having these intrusive thoughts as I was falling asleep so it would wake me and I'd have to sit up and sometimes even have to go and have a cup of tea in the middle of the night," she said.
Excruciatingly violent random thoughts are among PTSD symptoms endured by siege hostage Louisa Hope. (HANDOUT/SUPPLIED)
In August, she helped launch Victims of Terrorism Australia, a support and advocacy group for survivors of terrorist acts.
"After the siege, when I was lying on Phillip St, the one thing I knew in my heart was that we had to get something good out of what happened," she said.
"What happened in the Lindt Cafe happened to our entire country."
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