[Suzerain of Sheol]

Those two forms of address weren't exclusive. If you you know any French, they're similar to "tu" and "vous", with "thou" being a casual form of reference, and "you" being a respectful one. That probably seems backwards, and you can blame the King James Bible for that, since they thought it was best to address God as a friend, not as a superior (why?) and it's since been memetically accepted by our culture that "thou" is the formal form of address.