It probably happens very casually, just a “bye, ba!” that slips out of Si’er unthinkingly, probably as she’s being picked up by Sang Zan and Wang Zheng for her playdate with their daughter.
Yunlan is shook, and will probably remain so for the next couple of hours.
Shen Wei comes back home to a teary-eyed Yunlan who throws himself at Shen Wei, latches on, and refuses to let go.
“Lao-gong,” he murmurs by Shen Wei’s ear, and Shen Wei feels his heart skip a beat at the term even after all this time. “She called me ba today. She was just leaving the house and she said it. She smiled at me and she said bye, ba. She called me ba!”
lbr Shen Wei will probably start tearing up at this as well, they are both very emotional and very extra, HOW IS SI’ER EVEN GOING TO HANDLE THEM WHEN SHE STARTS DATING