What is peculiar about Mercury's revolution? What causes this oddity?

The oddity of Mercury's movement is due to large orbital eccentricity when compared to other planets.

Explanation:

In solar system, each planet revolves around the sun in their respective orbit. Mercury turns in a manner that is special in the Solar System. It is tidally secured with the Sun in a 3:2 turn circle resonance, implying that in respect to the fixed stars, it pivots on its hub precisely multiple times for each two upsets it makes around the Sun. As observed from the Sun, in a casing of reference that turns with the orbital movement, it seems to pivot just once in every two Mercurial years. An eyewitness on Mercury would hence observe just a single day each two Mercurial years.

Mercury's orbit has the littlest tilt of any of the Solar System's planets (about 1⁄30 degree) which acts as cause for unique movement of this planet.