Three people walk together

Three people walk Together，two people walk in front and one people behind. The two people in front whisper, the one behind follow them closely without any words.

Then, they find one place to eat barbecue, finally, the one behind participat in conversation. Talking, eat ing, leaving.

When they leave the restaurant, the atmosphere back to the before. I don't understand what make the relationship so complex.

Eventually, they decide to finish this meeting, one person leaving with taxi, another one and the behind one walking together. However, the two people in front still keep calling, and the one behind have to hear.

So, whether three people walking or two people and one people walking?