Atlas De Mornay is the brother of Amelia Croft. He was the executor of the Croft Estate until he lost it in a legal battle against his niece Lara Croft.
He held a grudge against Richard Croft, after his sister broke off her engagement to the Earl of Farringdon to be with him. He also blamed him for what happened to his sister.
His relationship with his niece wasn't any better, when Lara attempted to be courteous he callously brushed it off and stated that they shouldn't pretend to care about formalities or pleasant conversation. It was due to this attitude that Lara had not seen him in five years. Lara even imagined slamming his head on the table and throwing him out of a window in response to his rude, and stuck up behavior.
Lara went to meet with him in order to take control of the Croft estate, however, he refused on the grounds that he didn't think she was responsible enough in the aftermath of Yamatai, and told her to seek professional help.