Mercury ruled people often have conversations with themselves,through YOU.In other words, they often are "self-soothing" when conversing with you about worries and fears. Especially when Sun/Moon is Mercury ruled.
What they really aim to do with these conversations with you is say to themselves: "You see, I am a reasonable person. I have looked at every option from all ends and have considered the many ways that this could play out"
They are not looking for you to be the "aha" person and agree with every point made. In fact, if you care for them it may be beneficial for you to steer them clear of any chronic cynical thinking by providing an alternative "But have you considered this..."
Often times Virgo/Mercury ruled people (even Gemini) are relieved plenty when all the finer details have been ironed out and minor challenges and annoyances have been sorted.
The next time they tell you of their worries and fears, put a pound of "positive" rationale on one of them and see how they react.
They often like it when they have one less issue to worry about. And as a Sag whose had relationships overwhelmingly with Virgo Asc/Sun/Moon/Venus/Mars influenced people, I can say that from my experience they really LIKE it if you assist them in chasing away worries and fears.
Tea and sympathy is not enough for these folks. A practical solution or advice usually works best;especially one that you can demonstrate openly to work efficiently and quickly.