As we all know, Zhu Bajie is a lazy man who craves beauty. I used to be a canopy marshal in the Heavenly Palace, but I was punished by the Jade Emperor for molesting Chang 'e and became a pig. Although he followed the Tang Priest all the way west, his defects still exist. Not only that, Pig Bajie also loves the Monkey King very much, especially picking up things, and he is lazy when fasting ... Friar Sand has made mistakes before, but since,
According to common sense, if Pig Bajie and Friar Sand are people in real life, everyone will definitely be more willing to get along with people like Friar Sand and do things more reliably, but the Monkey King has a better relationship with Pig Bajie. And "Bajie", usually called Pig Bajie, also shows that the Monkey King and Pig Bajie are closer, at least closer than Friar Sand, so it will be more casual to call them by their first names, just like in college.
Then why is the Monkey King closer to Pig Bajie? You know, Pig Bajie has offended the Monkey King many times. Every time Tang Yan taught the Monkey King a lesson, Pig Bajie always echoed, and even encouraged Tang Yan to read a "hooping spell" to restrain the Monkey King. Two people had a grudge when they were in heaven. ...
And Friar Sand's character is a man show. Although he works hard and is practical, he doesn't talk much. Friar Sand looks a little fierce. Coupled with his serious appearance, natural communication with the Monkey King is less. Moreover, Friar Sand called the Monkey King and Pig Bajie "senior brothers" and never crossed them. His character belongs to that kind of steady and practical.
The Monkey King used different words to address his two younger brothers because of their personalities. Friar Sand is honest, so the Monkey King is serious, while Pig Bajie is slightly "not serious" compared with Friar Sand, and Pig Bajie often calls the Monkey King "Monkey Brother" instead of "Big Brother". The Monkey King sometimes calls Pig Bajie an "idiot" when he is short of breath, but the Monkey King has deep feelings for his two younger brothers.