Any more clues you night have may help us find them.

This is a possibility - looks like Patrick Phelan born Aug 1873 in Ireland and living on the 1900 census at East 39th Street. Manhattan, New York. Servant. Immigrated 1894 No further information. Living with a family and other roomers/lodgers etc.
Patrick Phelan Age 27

Looking at the passenger lists for Patrick Phelan 1873 birth has entries for 1892/1896/1898 but there are a number of others born 1871/1875. Dates can vary so he could be any of them
Still quite a number of choices -
Do you know if he married ?
Did he have a brothers called Michael and Phillip ?