The Halley's Comet has such a WEIRD orbit... How is this possible? What other than the sun is pulling?

Halley's orbit is atypical because it isn't symmetrical or even close to it. Plus, its center isn't the sun. Using a Newton or Relativistic Theory, can you explain how something could seemingly rotate around nothing? I'm a astronomy novice but it's all really compelling due to recent life experiences. Tks.