He lost his firefighter father on 9/11, and now a teenager could lose a $1.2 million inheritance, too — because his four greedy aunts are trying to keep the cash, according to a lawsuit.

Christopher Maffeo, 16, was supposed to get two Staten Island properties his grandfather intended to bequeath him, he and his mom claim in a suit filed against the aunts.

Grandfather Louis Maffeo doled out $4.8 million in cash and property to his adult daughters while he was still alive, giving each a Staten Island home and $400,000.

The teen and his mom claim that Louis, a retired city firefighter who also worked as a substitute teacher, had not finalized his estate plans for Christopher when he died in April.

The aunts initially agreed to “do the right thing” but then went silent about giving Christopher his share, according to court papers. The clash over cash has fractured the family and traumatized a young man.

“A young man that lost his father in 9/11 is now going to lose the rest of his father’s family over money,” lawyer T.J. Beinert, a lifelong Maffeo family friend, wrote in Staten Island Supreme Court papers.

Christopher’s mother, Linda Maffeo Melloy, said she was touched when Louis Maffeo offered to provide for Christopher, who has been “severely devastated” by his grandfather’s death. “The actions of his aunts have only made it worse,” she wrote in an affidavit.

Louis Maffeo talked about providing for Christopher’s “college, marriage and health care,” Melloy said.

Christopher Maffeo was just a baby when his firefighter dad, Joseph, 30, died on 9/11 while with Brooklyn’s Ladder Co. 101.

Joseph’s family — including his parents, Jean and Louis, and four sisters — launched a foundation in his name, raising money for charitable causes on Staten Island.

Jean Maffeo, an optician, died in December 2015. Over the years she and her husband amassed a roughly $6 million portfolio that included a half-dozen rental properties and cash, according to court papers.

Now the four aunts, PS 29 Principal Linda Manfredi, who runs The Joseph Maffeo Foundation; Donna Maffeo; Susan Drury; and Debra Morri, are allegedly refusing to give their nephew his share, according to the lawsuit.

The aunts have “self-servingly and unilaterally determined that they are the deserving parties,” Christopher and his mom charge.

Christopher is currently deciding whether to go to Princeton or Georgetown University, which both charge about $65,000 in yearly tuition, say court papers.

Beinert called the aunts’ actions an “injustice.”

He said he met with the Maffeo sisters after Louis’ death “with assurances from all of them they would do the right thing and make sure Mr. Maffeo’s wishes were followed and Christopher Maffeo would be included.”

The next day, the sisters stopped taking the lawyer’s calls, he claimed.

The attorney now believes the women intend to take Christopher’s share “and distribute it amongst themselves and their family members,” the lawsuit says. The aunts “have not explained this, have been acting very weird and refused to meet with us to review the issues,” said papers filed by Melloy, who remarried.

The aunts did not return messages requesting comment.