Then, she slapped her.
At 14, Hernandez was lonely and vulnerable. Her parents were divorced - her father was absent, her mother an alcoholic - and her friends were few.
With the threat of violence, the gangster had both intimidated Hernandez and offered her something she thought she needed.
"I thought by joining the gang ... that I would have friends ... and that I would have protection," Hernandez said.
After she let four male gang members beat her into SUR-13, Hernandez was without a doubt a "Sureño" or a member of the gang.
She wore dark blue, branded herself with a SUR-13 tattoo and never hesitated to fight when rival gang members ventured into her territory.
"I guess at that time, you know, we thought that, you know, we were fighting for something, for respect and to be known," Hernandez said.
Today, Hernandez acknowledges that she wanted to fight because she was always angry. After her parents' divorce when she was 12, Hernandez watched as her mother would get drunk and say mean things to her. Her father had pretty much disappeared.
"I felt alone, I didn't feel like I had any help from anyone," Hernandez said. "I guess that's why I wouldn't get out (of the gang) or anything, because I guess I felt relieved when I would get high or take out my anger on other people."
Her fellow gang members had similar backgrounds and needs.
Lt. Scott Ware, commander of the Gainesville-Hall Gang Task Force, said most of the gang members he encounters have joined because their emotional needs are not being met.
"Typically, there's a void that is met by gang members," Ware said.
Gangs create an opportunity for marginalized teenagers to connect, belong and feel respected, said Michael Holosko, an expert on gang behavior and a professor at the University of Georgia's School of Social Work.
"You wear your gang colors, you get a tattoo. It's like the military, you know?" Holosko said. "You put your uniform on and you're affiliated with something that immediately people recognize you as a part of."
The majority of Hall County's 370 documented gang members are Latino teenagers who come from fatherless homes, Ware said.
For Latino teenagers, gangs serve as a cultural comfort zone, Holosko said.
Joe Amerling, the vice president of the Georgia Gang Investigators Association and a local gang investigator, agrees.
"They came here as a minority, and for the most part, white people went after them and they bonded together for protection," said Amerling. "They have a fear of law enforcement, and there's always a fear of deportation and there's always a lack of trust."
Black gangs formed for similar reasons 30 years ago, said Bobby Jones, a school resource officer at C.W. Davis Middle School.
"There was a need for everybody to huddle together," Jones said.
But today, the majority of gangs in Georgia are Latinos, Amerling said. Aside from the need to stick together, the gang culture perpetuates the Latino ideal of machismo, he said.
"In the Hispanic culture, the male is the dominant role model regardless, you know?" Amerling said. "If he's 14 and there's no dad in the household, guess what? He's running things, and mom's going to be subservient to him and so are the sisters. And that's just how it is."
But "how it is" becomes a dangerous place to be. Just two weeks ago, Juan "Baby P-Nut" Gomez became the first person in seven years to die as a result of gang violence in Hall County. Gomez, who was 16, grew up without his father. His brothers, members of La Onda 05, were his role models, said their sister, Martha Garcia.
Before Gomez died, he had followed in his brothers' footsteps and had risen through the ranks in the gang to become a shot-caller.
Hernandez also gained respect as a gang member. Not long after she joined SUR-13, Hernandez had become a notorious fighter that fellow gangsters would call on when they needed support.
She had also become a high school dropout and a drug addict who spent a month in a Texas jail after running away to Mexico when she was 15.
Amerling was the main reason that Hernandez got out of the gang, she said. The investigator would speak to her on the streets, and remind her that as a bilingual resident, she could make a better future for herself than to be a frequent visitor of detention centers.
Hernandez calls the investigator a friend who was there for her at her lowest point in life.
"Somehow he got close to me," she said. "I felt like he believed in me. ... I felt like he was the only one who saw why I was doing everything and why I was the way I was."
Now, Hernandez is a happily married 24-year-old who is trying to get her GED so that she can go to college and study criminal justice.
But she said leaving the gang was difficult. At 17, Hernandez decided she did not want to be a part of the gang anymore. But she said every time she would try to separate from the group, her fellow gang members would come find her at home.
Where teenagers live is just as big a factor in whether they join a gang as their need to belong, Amerling said.
Hernandez was recruited by SUR-13 partly because she lived on Stringer Avenue. Likewise, the Gomez brothers grew up on Atlanta Street in La Onda territory.
"Kids that are involved in sports and in church and who are in school normally aren't going to be in a gang," Amerling said. "But it's the neighborhood's problem, too. Sometimes, to get away from a gang, you've got to move from the gang."
Hernandez was able to move before it was too late.
And today, all that remains from her gang days is regret, a rap sheet and distrust of her peers.
Hernandez still has the SUR-13 brand on her arm and three dots next to her eye, which remind her of "Mi vida loca" or "my crazy life" as a teenaged gangster. But she has covered up the "laugh now, cry later" tattoo that gang members get to justify their reckless behavior.
"I know that I wasn't a good person back then, and that I did a lot of bad things," she said. "Now, I look back, and I know I'm really lucky that I changed my life around and that I didn't end up ruining my life."