Nathan, who struggled with drug-related mental health issues, had been desperately trying to get help in the days before his death - and had been due to see a psychiatrist yesterday.
Instead, around 100 people gathered in Belfast's High Street to pay heartfelt tributes to the troubled young man.
At last night's vigil, friends, family and homelessness volunteers lit candles, hugged each other and shed tears as they mourned the death of their friend.
Karen Boucher of homelessness charity Haven said: "Nathan was a good man. He may have had his hardships, and he certainly went through a lot. He wanted a better life, and was still struggling with his demons. He was determined to get back on the straight and narrow.
"It's so sad that a young life has ended so soon. Nathan was such a wee gentleman. We don't want to lose any more."
Gary McDonagh, one of Nathan's friends, added: "Nathan was a real good kid. Him and his girlfriend Sophie did so much to help the older homeless people. We're all really shocked that he's gone. We'll miss him."
Nathan's mother and stepfather attended the vigil, but were too upset to talk about their son.
Nathan's girlfriend, Sophie Tweedie, said the system had let Nathan down. "He wanted more help, but he just didn't know how to go about getting it - and now it's too late," she explained.
She last saw Nathan on Thursday night, just before he died.
"Everything was getting on top of him - he was really emotional and upset," Sophie said. "I can't get my head round it at all."
The site at Divis Street where the young man died is now garlanded with flowers in his memory. Nathan's funeral takes place tomorrow. Details have not yet been finalised.