the sun - Motion of the sun as observed from mercury

Before about 1966, Mercury was thought to be tide-locked, almost half always sunlit and another near-half always dark – as most moons, including ours, are tide-locked to their primaries, and for the same reason. The difference in the strength of the primary's gravity between the inner and outer ‘poles’ creates a force tending to pull those points away from the center of the satellite, along the line joining it to the primary. If the satellite is ellipsoidal rather than spherical, the tide will tend to align the ellipsoid's long axis to the primary.

But Mercury's orbit is so eccentric that the strength of the solar tide varies by a ratio of 4:7 (if I've computed correctly). The rotation rate nearly matches the revolution rate at perihelion, when tide is strongest and Mercury is moving fastest; if the match were perfect (if the orbital eccentricity were a bit less), the sun's apparent path would have cusps rather than little loops. Presumably the imperfection is because the tidal effect does not vanish away from perihelion.

The loops have nothing to do with axial tilt; Envite was probably thinking of the analemma.