Mercury square Lilith (orb 5.2°) creates concrete friction between the two planets. The orb is moderate; it stays secondary beside tighter signatures.
Here, Mercury in Sagittarius in House 7 brings intellect, language, thought, and technique into House 7 (relationship, confrontation, and the mirror of others), with Sagittarius style (expansion, travel, belief, and the search for meaning); Lilith in Pisces in House 10 brings pure ideal, absolute demand, fascination, and refusal of compromise into House 10 (vocation, status, responsibility, and public image), with Pisces style (imagination, faith, compassion, dream, and permeability).
Concrete friction: this aspect creates tension between thought, speech, obsession, purity demand, and refusal to let go. Visible angle: Mercury near the Descendant (orb 3.1°) touches an angle; this aspect is easier to notice through direct relationships, partners, opponents, and the way others are met. House 7 (relationship, confrontation, and the mirror of others) is in friction with House 10 (vocation, status, responsibility, and public image); this can create blockage, inhibition, overreaction, or repeated conflict between the two fields.