Many thanks to Hyfrydle (had to scroll down to check spelling
I found this wonderful game due to your LP, I'd subbed after your Project Zomboid one.
This does seem to have gone rather off topic but....
'Baron' or 'Vassal' sound good.
'Lord' is too similar to 'Overlord', sounds a bit clunky. If I'm understanding the lore right, these lieutenants were either beaten into submission by the Overlord or wished to serve them as a form of protection after discovering their power.
Could always go for 'Deputy HR Manager'.