Mourners at the funeral of Billy McConville have spoken of his strength and compassion.
Mr McConville, whose mother Jean McConville was murdered by the IRA in 1972, died at the weekend from cancer.
After his mother was abducted he was taken in care aged six.
In 2014, Mr McConville told the Historical Institutional Abuse Inquiry he had been abused by some De La Salle Brothers and physically abused by a lay teacher in Rubane House, County Down.
Despite his "lifelong nightmare", a priest told mourners he laughed and bantered to the end.
Mr McConville was 50 when he died.
Jean McConville was murdered and secretly buried on a beach in County Louth by the IRA. Her body was not found until 2003.
'You built your bridges to everyone'
Mr McConville's funeral was held in St Paul's in west Belfast.
His daughter Aime said he was "strong and unbelievably brave".
"You built your bridges to everyone and you brought your family back together," she said.
"Rest in peace dad, I love you and I will miss you."
Fr Patrick McCafferty said the abduction of his mother had been the "cruellest of misdeeds".
He also called on politicians to implement the findings of the Historical Institutional Abuse public inquiry.
"They must do so, immediately, as a matter of urgency," he said.
"All of society has an obligation to make reparation to these sisters and brothers of ours, who were so deeply wounded during their tender years."
Former First Minister Peter Robison has also called for immediate action to compensate abuse victims after payments recommended by the inquiry were delayed due to Stormont's collapse.