As as Lawyer Pres. Lincoln knew that Fido
meant "To Trust/Confide/Depend" in Latin.
> Spymaster Fido = weird dog nickname
Fido (ca 1851 – 1865) was a yellow mongrel dog owned by Abraham Lincoln and kept by the family for a number of years prior to Lincoln's presidency, and became a presidential pet during Lincoln's presidency, although he remained in Springfield, Illinois.