These links are to Ford pubs to do with the OBD2 system and electrical system, but give a lot of info relevant to various topics now under discussion - why the ICE runs , what actually pumps the fluid for the heater (there are 2 electrical pumps) , a variable speed fuel pump dependent on demand, great diagrams of the power flow and -bonus - a cure for sleeplessness! Some of it's pretty tedious LOL.
The first is emissions related and the second is for modifiers like police depts. What i found interesting was a table for all electrical draws in a stock hybrid. Radio and one seat heat are almost the same.
I didn't cut and paste pages because some may want a more detailed description of what's actually happening than others.
I don't know if anyone else has linked these before, if so I apologize.