My grandfather was Hagop (sp. Akop) Atikian. After the genocide in the Ottoman Empire, he and his sister, Zaghig, were the only known survivors. He never knew if any other siblings lived to immigrate to the US. My grandfather was from Kessab, Syria, but spent some time in Aleppo and Beirut as a teacher. He married Efronia Churukian before immigrating, and they adopted her nephew as an infant.
If you had a grandfather named Atikian who immigrated any time after 1885, he is probably a relative. It is not a popular last name.
In the US, my grandfather, Hagop, lived in Paris, Illinois, Boonton, NJ, and Hollywood, CA, where he died in 1977 or 1978.
Armenians are hard to track genealogically because of the genocide. Family trees and other administrative records were often kept in the libraries of churches, as monks were literate and doubled as scribes. Those churches are mostly destroyed and the writings burned. In addition, so many people dies that in some cases, entire families were wiped off the face of the earth. It will be very hard to track any relatives without a DNA test.
I wish you good luck.