When Maria married CTR at her mother’s residence on March 13, 1879 (service conducted by John H Paton) her younger brother, Lemuel, was likely one of the guests. Unfortunately, the modern practice of group photos for weddings was not applied to this particular wedding, so we are left with supposition. However, Lemuel was born in Allegheny in 1857 and is found in the census returns there for 1870 and 1880.
The photograph comes from the volume Chicago Biography from c. 1891. The text mentions that he had been a reporter on the Pittsburgh Dispatch and Pittsburgh Commercial Gazette from around 1879-1883. He then went to Law School in Michigan from 1883-1885, and moved to Chicago in 1887.
When Maria left CTR she first went to Chicago to stay with Lemuel.
Lemuel death made the news. He was murdered in court by a disgruntled police sergeant in 1921. The story is found in the New York Evening World for July 29, 1921. One wonders whether Maria traveled to the funeral.