Alright, this is something me and a friend of mine sorta collectively noticed. In Bonehunters, that weird thing which gets freed in the prologue (Trobarahl?) is near Y'Ghatan at some point, and it's thinking about how it's old name was "Yadath Garath."
Now, I find it interesting that Lady Envy has a pup named Garath wandering around with her. And I find it even more interesting that the original names of the seven holy cities are also supposed to be the named of the seven deragoth who are alive today.
Or were, before you-know-who.
I'm a little rusty on MOI, and anything which might have given further insight into Garath's origins and such. Except that my friend said that at some point, Envy says something like "oh, he could be a shadow hound if he wanted to." ?!?!?!?