There was a John Caesar Christian born 1886 to John Robert Christian and Isabella Boyde.
He may have married in 1920 . The details can be found in www.lawsons.ca together with other siblings if you search birth, marriage and death indexes.
John Robert Christian came from Douglas but his father Caesar came from the parish of German and his mother Isabella Maxwell came from Lonan. The family lived at the Alma Hotel in Douglas where Caesar was the publican.
The hotel details can be found in Manx Notebook if you search 'Alma'. One of John Caesar's brothers was called Henry Alma presumably after the hotel.
Caesar Christian and Isabell Maxwell married in Braddan in 1857 aged C53 and C37 which may indicate a previous marriage
Do you know thw maiden name of your Grandmother- the wife of John Caesar?