Christine Smith QC was speaking in Northern Ireland's Historical Institutional Abuse inquiry at Banbridge Court in Co Down (pictured), which is examining allegations of abuse in Catholic, Protestant and state institutions in the nation from 1922 onwards.
She was referring to abuse which occurred at Manor House, a former children's home in Lisburn, near Belfast, in the early 1970s.
Ms Smith said: "He took children on day trips, played football, and admitted having feelings for MH41 [one of the residents].
"He admitted abusing MH41 at his own home."
The barrister also said that a decision in 2004 was made not to prosecute the alleged abuser.
A man, now in his 60s and living in Australia, told the court via video link that the former soldier "manipulated us children."
He also said: "I think he may have abused other children.
"I believe we were just pieces of meat to that man that abused me."
Another man also in his 60s also accused the soldier of being "a freak visitor to the home", and that he abused children "many times".
The Society for Irish Church Missions, a Protestant mission group linked to the Church of Ireland, ran Manor House at the time of the alleged abuse.
It has issued an unreserved apology for any abuse which the soldier may have inflicted, calling him "an opportunistic, determined and devious abuser."
Separately, there was also claims of "sexual touching" among children at Manor House.
In one case a girl was allegedly sexually assaulted by another child. He was moved to a different home.
And in another case one offender was on bail for an offence at a home run by Barnardo's, when he was accused of another assault involving a Manor House resident.
