I mean your Overlord is your character, but its responsibility is more towards managing its assets and operations. You have goals set for you and you need to try to meet them or suffer consequences.
You have choices, you have your own will but in this case you've got a boss in Mother Brain...
Went ahead and did a write up of my Overlord and his methods/group. Something insidious over more open alien methods. An evolved Color Out of Space that has learned the value of manipulating and empowering its hosts instead of eating them.
The Void Whisperer
It fell from the sky, a meteor of...
That is true, whatever is resonating with you most for running a story is likely the best option or options. I'd give anything a shot aside from what I offered up as my inerests.
Updated
Julian Cromwell, voice of the Cromwells and blood sorcerer died in the Audience Chamber of the Tower of Rule in Amaris. A party of adventurer's linked to the conspiracy against the family attacked the Tower, killing their way to the top where Julian was waiting for them in his full...