JJ holds the HIV medication she is is finally able to swallow. (Marvin Joseph/The Washington Post)

JJ stepped off the yellow school bus and, still giggling, waited for two friends. She had just finished her first day of seventh grade, and as the three girls walked up the street, they took stock of their new teachers, rules and classmates.

“I got homework from the first day from science,” JJ lamented, a stuffed pink backpack hanging from her shoulder. Three boys trailed behind, desperate for the girls’ attention. One ran ahead and yanked on an overhanging tree limb, showering leaves across the sidewalk. JJ, 11, rolled her eyes. Wearing azure-blue jeans, a checkered white shirt and a fresh pair of Air Jordans, she didn’t look or act any different from her friends.

But JJ has a secret.

Last summer, the doctors at Children’s National Health System hospital in Northwest Washington revealed to her that she was born with HIV, a moment detailed in a Washington Post story. Her caregivers told her the truth, in part, because they hoped it would help motivate JJ to take the powerful pills she had so long struggled to swallow. For months after the disclosure, she made no progress. But now, as her 12th birthday approaches, JJ has had a breakthrough. She is finally swallowing tablets instead of relying on less effective liquid medicine, an enormous milestone that could lead to a healthy life for decades to come.

Last summer, JJ spent an afternoon at her neighborhood playground after learning she was born with HIV. (Marvin Joseph/The Washington Post)

Not long ago, though, no one knew whether she would ever get there.

JJ was first taken to Children’s as a gravely ill infant who, along with her siblings, had been removed from their biological family after allegations of molestation against an older brother. Her father was a convicted murderer, and her mother had abused drugs.

At 4 months old, JJ began to live with a Washington-area woman named Lee, who worked as a bus driver and foster parent. (To protect her privacy, The Post is identifying JJ only by her initials, and her mother by her middle name.)

When JJ was 3 and her sister was 9, Lee adopted them both. A few years ago, her sibling, in a moment of spite, told JJ that Lee wasn’t their real mother. The girl never got over it, and learning she had HIV only made her fixate more on the circumstances of her childhood.

“Why was I adopted?” JJ had written in a notebook that she took to the first appointment at Children’s after she learned the truth about her condition. She never asked the question.

JJ rebelled in the months that followed the disclosure, throwing random tantrums and often refusing to take even her liquid medication. She started to fail math and reading.

Lee, now retired and in her 60s, didn’t know what to do. She considered sending her daughter to an all-girls boarding school. She prayed for help.

JJ colored this picture of a Care Bear with crayons the day she was told by her doctors that she has HIV. (Marvin Joseph/The Washington Post)

“She was so hurt,” Lee said, “and she didn’t know how to express it.”

One of JJ’s doctors, Kathy Ferrer, had seen that reaction many times before. Certain children, she said, process the news immediately, while others take months.

“Some,” she added, “never end up really being able to cope with it.”

Ferrer hoped JJ wouldn’t be in that last category.

At one appointment, she at last asked her doctors why she had been given up as a baby. Her biological mother couldn’t take care of her, they said, but Lee could — and wanted to.

Still, she remained defiant.

In April, Ferrer decided that they could remain patient no longer. JJ’s CD4 count, a measure of the immune system’s health, had gradually declined. From a high of more than 2,000, it had dipped to a low of 365. AIDS is diagnosed at 200.

Ferrer and other staffers who had cared for JJ since she was a baby confronted the girl about her attitude and insisted that she take responsibility for her own health.

The pressure worked. JJ agreed to try the pills.

“I have your word?” Ferrer asked, and JJ gave it to her.

The doctors started her on a 150-milligram tablet (about the size of a Tic Tac) meant to be taken twice a day.

It was around then that JJ also attended a military-style boot camp for kids. She excelled, able to do more sit-ups — about 40 — than most of the boys. She practiced pull-ups and one-mile runs. She scored a 24 out of 25 on her final exam.

“The sky is the limit,” one instructor wrote of JJ’s potential.

Her improved self-confidence made her more willing to take the medication.

In June, doctors switched her to a 300-milligram pill (nearly the size of a Mike and Ike), and she reluctantly embraced the new challenge. Her CD4 count climbed to 659.

The disclosure, Lee and the doctors realized, had finally begun to pay off.

JJ knows that she misbehaved in the months after learning about her HIV, and she knows why, too.

“Because it was new to me and stuff,” she explained while sprawled on the floor of her living-room carpet, about an hour after getting off the bus.

She had never fully understood why no one could touch her blood or what all those medications did to her. Now she does.

For years, Ferrer has explained JJ’s illness to her with an illustration. She draws a long-haired stick figure surrounded by circles, or cells, called “soldiers.” She slashes X’s through several circles, demonstrating what germs do. And what do the medicines do? They destroy the germs.

In July, Ferrer had just begun the sketch when JJ interrupted.

“Let me do it,” she said.

JJ drew a tongue topped with two pills — one for HIV, the other for allergies. She added a bottle, inscribed with “CVS,” that shot arrows into the germs.

“I’m in a happy place,” she wrote on the page.

The drug she’s on now is meant only to keep the virus under control, but when JJ is ready — maybe soon — she’ll transition to a more aggressive regimen of either four small pills or two large ones.

Controlling the virus will become even more important as she gets older. Lee has already begun to tell her daughter how fraught dating could be, and JJ knows that disclosing her illness to anyone, which she still hasn’t, is potentially dangerous.

But every day, she looks and acts and sounds more like a teenager. In the past year, she has grown from 5 feet to 5 feet 2 inches. A reality dancing show called “Bring It!” has replaced “SpongeBob SquarePants” as her favorite TV program, and she no longer fears the mechanical mouse at Chuck E. Cheese’s. Soon, JJ hopes to become a cheerleader.

In so many ways, though, she’s still just a kid.

It showed that evening when she went upstairs to her bedroom to spin around until she got dizzy, and when she returned to the living room wearing Mickey Mouse ears, and when, in a moment of panic, JJ realized that she’d forgotten to get a picture in her first-day-of-school clothes, so she put them back on.

And then came 7:52 p.m., when Lee told her daughter to take the medication.

JJ plucked her bottle from a table next to the sofa and walked to the kitchen.

“Where’s my princess cup?” she asked, before she found the glass decorated with Disney characters and filled it with fruit punch.

JJ then gave the bottle to Lee, who removed a pill and handed it to the girl. JJ opened her mouth, threw it in and took a long swig, but didn’t gulp.

“You swallow?” her mom asked.

JJ shook her head, no.

She picked up the cup and drank more until, at last, the pill went down. She stuck out her tongue to prove it.

Then, as if she had done nothing remarkable, JJ took her princess cup back to the kitchen, turned on her Wii and danced.