My friend @shadowweirdo has a theory that the reason why Varian looks so different from Quirin is because of the opal. We see Quirin get blasted by the opalâs magic in the flashback. (s2e1) It could be entirely plausible to say that the opalâs magic contributed to Varianâs physical features.
ie: black hair / blue streak , pale skin , blue eyes ; all of which look like a humanized version of the rocks.
      The rocks are destructive, and so is Varian. Barring his status as the s1 villain aside, heâs clumsy, has a penchant for bad luck, and somehow, someway his inventions tend to destroy everything around him. Even the biggest rock formation in Corona turned up smack dab in the middle of Varianâs house of all places. The rocks completely destroyed Old Corona without a trigger.Â
More than anywhere else, they grew in Varianâs village, so much so that the entire populace had to evacuate.
      Not to mention that Varian speaks FOR the rocks in Rapunzelâs prophetic dreams. Each time she dreams about the rocks, Varian is there. The rocks follow him, react along with him, and his anger towards her mirrors that of the rocksâ destruction as they moved towards Corona proper.Â
      Varian is also the only one (besides Adira, who we KNOW is from the Dark Kingdom and connected to the rocks and opal) to tell Rapunzel to âFace her Destinyâ, and we all know that Rapunzelâs destiny ties in directly to the rocks.
      In essence, because of the traces of opal magic passed down from Quirin to Varian, thus effecting Varianâs physical appearance, the rocks see Varian as âone of themâ. They use his visage to speak to Rapunzel, creating yet another mirror between Varian and Rapunzel: the sun and the moon.