A tall and handsome young man was walking with a pretty young lady in a white dress on the Avenue of Stars in TsimShaTsui East. A couple of steps behind them walked an older lady. The young man turned and said something to the young lady in Putonghua. They stopped. The older lady pulled out a bottle of water and passed to the young man. He drank from the bottle and continued walking.
He finished drinking and without stopping nor looking back, passed the water bottle to the young lady, who passed it back to the older lady, who put it back into her bag. Neither the young lady nor the older lady drank.
What was the relationship among them?