Vasile and Florentina Mutu with their children in Olteni, Romania, the village where they grew up.

Extended family lives nearby and often gathers for meals.

The family makes finely honed brooms and axes out of wood, a trade passed down through generations of their ancestors.

Though most of their children had been born at home, Constantin had to be delivered by C-section. Vasile sold two pigs and a cow to pay a doctor to do the procedure. In a haze of pain while she was in labor, Florentina signed documents that she couldn’t read. When she returned to the hospital for an appointment to check on her recovery, a hospital employee told her that the doctor had also performed a tubal ligation. She and her husband had planned to have more children, as is traditional in their culture. They were devastated.

Soon after, in between middle-of-the-night feedings of Constantin and while the rest of their children slept, Vasile and Florentina formed a plan: They would try to seek asylum in the United States with their two youngest children and send for the others when they were settled.

Within weeks, the Mutus had sold their home to pay a man who would arrange to get them into America through Mexico. Florentina packed a suitcase with diapers, a change of clothes for each of them, holy oil and dried basil — a Romanian good luck charm. On the plane, Constantin started to run a fever.

Mexico City was a whirl of chaos and noise. They couldn’t understand the voices or signs in Spanish. Beggars banged on the window to their taxi to ask for money; though they had done the same themselves in Europe, it somehow seemed scarier. They met a smuggler who led them to a crowded bus headed for the border.

The Mutus found seats out of sight from one another, and for the next several hours, took turns caring for Nicolas, their 4-year-old, and Constantin, who was getting warmer. As they approached the border, they got off at a stop and split up to look for medicine. Mr. Mutu had settled into the last leg of the journey on the bus when Constantin started crying on his lap. Mr. Mutu stood up, shimmying toward the back of the bus to get a bottle.He spotted the seats where his wife and son had been sitting, which were now empty.

Mr. Mutu looked around frantically and pulled out his phone to call his wife, but both of them had drained their minutes by making calls back to Romania to check in with their other children. Unsure of what else to do, he paid a cabdriver to take him and Constantin to the foot bridge into the United States, thinking that he could call his wife when they reached the other side. It was dark outside when he reached an immigration officer stationed outside the American border. He told the officer that he wanted political asylum and was taken in to be interviewed with the help of an interpreter on the phone. Mr. Mutu explained that he had lost his wife and son, and that they were fleeing persecution in Romania.

Florentina praying at a monastery near the family’s home. She sobbed when she was finally able to see Constantin on a video call arranged through a social worker.

A handful of officers entered the room. They took Constantin, placed him on a chair, and shackled Mr. Mutu’s hands and feet.

“The police wiped the floor with me,” he said through a translator, explaining that he was dragged out of the room while Constantin stayed behind with some of the officers. “I started crying because I didn’t know what to do,” he said. “I couldn’t speak English. I told them, ‘I don’t understand. Why?’”

Florentina Mutu was still at the bus stop with Nicolas, crying on a bench since she had discovered that the bus had pulled away without her, when she got a call from her mother. Border officials had reached her in Romania and explained that she would also be arrested if she crossed the border. The relatives quickly scraped together money to get them home.

***

Constantin was placed with a foster family in Michigan while Ms. Acevedo worked to connect with his parents. She got a phone number for his mother in Romania and made a video call during what was the middle of the night there. A disheveled woman answered, sitting in darkness, looking like she had just been woken up. She spoke frantically, but Ms. Acevedo couldn’t understand, so she pulled up Google Translate on her computer and typed a message about Constantin in English, which she then played in Romanian.

Florentina Mutu started to sob. She repeated her full maiden name, which was listed on Constantin’s birth certificate, over and over. “She said it like 20 times,” Ms. Acevedo said “She said, ‘Florentina Ramona Patu,’ and I said ‘Yes, yes, yes.’ I just wanted her to know that he was somewhere. He wasn’t lost or disappeared or something. I wanted her to know that he was with people.”

Ms. Acevedo started making weekly video calls between Constantin and his mother, propping the baby up on the couch. Ms. Mutu would mostly cry as she spoke desperately to him in Romanian.

Vasile Mutu, still in detention, sank deeper into depression. He couldn’t sleep and refused most of the food that he was offered. Occasionally he was handed documents in English or Spanish, which he couldn’t read. He cried so much that his cell mates started beating him to make him be quiet. He thought about committing suicide. “No one was telling me anything. They kept telling me to wait and wait.”

Two months into his detention, an immigration officer came to Mr. Mutu with an offer. As he understood it, if he gave up his claim for asylum, he would be deported back to Romania with Constantin. He agreed, and on June 3, 2018, he was released from his cell and loaded into a van.

He looked everywhere for Constantin and asked the officers where his son was, but was not given a clear answer. At the airport, he refused to board without the baby. The immigration officers, he said, told him that Constantin would be handed to him once he had taken his seat. But the plane lifted off and the baby never came.

When Mr. Mutu arrived home, it felt more like walking into a funeral than a celebration.

***

While the months dragged on waiting for his day in immigration court, Constantin settled into a routine with his foster family, in their comfortable brick house on a hilly road in rural Michigan. The family, which had started fostering immigrant children a year earlier after a life-changing experience doing missionary work in Ethiopia, asked not to be identified in this story because it would violate the terms of their contract with the federal government. Their three daughters immediately became enamored with Constantin and would argue over who could pull him out of his crib when he woke up from a nap.

The baby’s foster mother meticulously documented his developments for Ms. Mutu, keeping in mind how hard it would be to miss moments like when he first scooted across the living room floor or developed the belly laugh that shook his whole body. “He would do new sounds or something, and they only do it for a short amount of time, and so you want his mom to be able to hear that,” she said. “And she always wondered if he had teeth yet, and so when he would smile, you could see. So I just wanted her to see that.”

She poured herself into caring for Constantin while she struggled to fathom how he had come into their home. “I can’t imagine being the person who grabs a hold of a child and takes them. I don’t know where you have to go in yourself to be able to do that job,” she said. “If we were in that situation, I would want someone to take care of my child. I would want them in a home, in a bed. I would want someone asking them, ‘What snack do you want before you go to bed at night? Do you want a pink toothbrush or a green toothbrush?’” she said. “Or rocking them in the middle of the night, helping them go back to bed when they have bad dreams.”

Constantin was still in diapers when he appeared in federal immigration court in Detroit, four months to the day after he had arrived in Michigan, on June 14, 2018. During the five-minute proceeding, he babbled on his foster mother’s lap as she sat on the defendant’s bench. His pro bono legal representative requested that he be returned to Romania as soon as possible at government expense.

A lawyer for the Department of Homeland Security argued against the request, stating that as an “arriving alien,” Constantin was not eligible for such help. The judge quickly ruled against her, questioning the idea “that the respondent should be responsible for making his own way back to Romania as an 8-month-old.” The judge granted the request made on behalf of Constantin, giving the government three months to either appeal or send him home.

By the time Constantin’s travel plans were booked for July — a few weeks after President Trump, facing a wave of public outrage, had rescinded the family separation policy — he was 9 months old and had spent the majority of his life in the custody of the United States government.

Florentina and Vasile Mutu didn’t sleep the night before the reunion. They were standing at baggage claim at the airport in Bucharest when they finally spotted Constantin, hours behind schedule, bobbing toward them in his foster mother’s arms. She handed the baby to his mother, but he screamed and reached back in the other direction, his face crumpling into a knot of terror.