Overall: There’s cautiousness in communication or thoughts. Sense of material security, safety and conservatism may colour thoughts and learning style. At its worst, there could be a fear or blockage when it comes to connecting mentally with each other. Like a headmaster and a student.
One on one: Saturn has a stronger effect on Mercury than the other way around. Mercury might feel that his or her words and thoughts are blocked or constraint by Saturn. Saturn can be rather critical, judgmental towards the mental attainments and ideas of Mercury. Mercury may feel belittled, worried or even mentally depressed. The confidence of Mercury in his or her mental ability may take a beating. Saturn may feel irritated by Mercury and perceive Mercury to be careless.
Positive manifestation: With conscious and deliberate awareness and adjustment, there is the potential for realistic and practical communication, thoughts, learning. Having a responsible attitude towards siblings.