With Mercury in Cancer, their inner communication can be poetic, though they may find it hard to share. When they do not feel at ease, they may stay silent or answer in monosyllables. Then, among their friends, they may talk, laugh and act spontaneously. The difference lies in the security they find in each bond.
The key word is trust. Sharing something of yourself first can help them talk about what is theirs. Reciprocity and a genuine interest in listening to them encourage conversation; respect the time they need before opening up.
At times they seem to ramble when you ask them for concrete facts, even if they were paying attention. They may find it hard to put a memory in order or to turn their inner experience into a precise explanation. In new settings they need time to get familiar with people.
That they express little does not mean nothing affects them. They may register situations that seem to roll off them and build up discomfort without saying so.
At an unexpected moment, complaints surface about something that happened long ago: the voice breaks, tears come or the reaction turns intense. Someone who only sees the immediate episode may not understand that, for this person, it was the last straw.
Respecting their silence can make it easier for them to open up, but mutual understanding also needs words. An attentive look does not always tell you what has hurt or what is hoped for from the relationship.