Was introduced to the concept of King Baby years ago while in treatment...now apparently, times having moved on, it's referred to a king or queen baby
King (or Queen) Baby | Psychology Today
There is a Hazelden version (had my own personal copy - speaks volumes ;-) but couldn't find that
King baby is one possible take on an inability to take responsibility, lean on others, which could, roughly translated, be seen as a lack of maturity...
Hated it at that time, but reading now some 22 years on (where did all that time go?!!) it rings pretty accurate for me at least.
Interesting question, thanks for posting