Mercury square Lilith (orb 4.9°) creates concrete friction between the two planets. The orb is moderate; it stays secondary beside tighter signatures.
Here, Mercury in Leo in House 12 brings intellect, language, thought, and technique into House 12 (retreat, contemplation, long time, and possible confinement), with Leo style (presence, pride, creation, and the wish to be seen); Lilith in Taurus in House 10 brings pure ideal, absolute demand, fascination, and refusal of compromise into House 10 (vocation, status, responsibility, and public image), with Taurus style (nature, good food, physical sensuality, roots, resources, and perseverance).
Concrete friction: this aspect creates tension between thought, speech, obsession, purity demand, and refusal to let go. Visible angle: Lilith near the Midheaven (orb 0.7°) touches an angle; this aspect is easier to notice through social role, reputation, career, and public image. House 12 (retreat, contemplation, long time, and possible confinement) 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.