With Mercury in Capricorn, voicing an opinion may be hard for them: they need to feel sure of what they know. When they do decide to speak, it is usually because they feel they have mastered the subject; then they may take the lead in the conversation.
When a romantic relationship is beginning, they may find it hard to take the first step. They may circle around the matter, show their charm or share their knowledge while waiting for the other person to take the initiative. They often know more than they express, and recognition of what they get right can help them trust that knowledge.
They do not like being interrupted while concentrating. As in the descriptions of Mercury in Taurus and Virgo, the expression of feelings may be reserved, while commitment shows in the value they place on their word.