Early on, he's usually called by others as Major Lu (魯提轄).
His original name is Lu Da 魯達
He then receives the Buddhist name Zhishen (智深, profound wisdom) during conversion.
Erniang is way more popular than her ranking in the 108 Stars of Destiny.
This is of course in part because she is one of the only 3 108 Stars of Destiny women. But her story about making human mantou is particularly fun!
She's also quite seductive, which gives directors a good opportunity for a bit of fan service. See e.g. kknews.cc/history/6epp2pp.html for a still from The Water Margin showing some good cleavage for example.