Devi Simhika - Mother of Svarbhānu (later known as Rahu & Ketu)

Daughter of Hiranyakashipu, Sister of Bhakta Prahlad.
Devi Simika was booned by Brahma to control the Shadow, she was the controller of Devi Chaya/shadow the mother of Lord Shanidev & wife of Sun.

The Father Sun God is energy source and chaya/mother is like an Umbrella always, we get comfort under the shadow of a tree similarly DEVI chaya is the motherly side of The Sun.

Simhika was so powerful that it's been said in one text, the birth of Hanuman was to kill Simhika.

Rahu & Ketu are similalry known as shadow Grahas, however because this material world is so Illusioned & Rahu/ketu controls this. They are the King & Beggar makers graha in astrology. From extreme to the most fallen.

The Sutra - With whomever Rahu sits, would behave according, comes from the story of Mohini avatar.
So after the immortality nectar/amrut appeared from the churning of the milk ocean/samudra manthan, the necatar was suppose to be distributed among the devtas & danavas equally.

Mohini cheated by putting the danavs under an illusion of her beauty & make them wait for their turn to have amrut, she distributed most of it to The Devtas. From the danavas side, Sarvabhānu was very focused & understood the trick played by Shree Vishnu in Mohini form,

so he took the form of a Devta & had a sip, he sat between The Sun & The Moon. They both complained & his neck was chopped by the Sudarshan chakra by Shree Vishnu.

God knows what's happening, he already knew about Sarvabhānu however he wanted to set an example & it was very much necessary for the creation.

Because he sat with devtas/good planet, he has devtas like quality & when he sits with danavas/mallific, he behaves accordingly.

Because he had amrut, so he gives good results, long term results, life chanfing and because he is also a danava consuming Varuni madira so gives mallefic results.

When he sat between The Sun & The Moon, they compalined & the head got chopped due to which, he hates these two graha & wants to eat them up, The Eclipse. Now because Rahu doesn't have a body so even after swollowing The Sun & Moon they pass out form the neck portion.

If we see this as per The bhakti point of view. Even a sinner sitting among Saints, with their aura they turn to a saintly/devta person. This is Ketu with exalted or friendly Jupiter.

The Time when Sarvabhānu decides to drink amrut is the Exaltaion (Gemini or Taurus axis) & the time his head gets chopped is when it behaves debilited.

So Rahu had the desire to rule the whole Universe & when the head was chopped, whatever he puts within him comes out easily as his body is illusionery and without a body but if a benific planet aspect or sit, it can sustain whatever he desires & can make turn a person to The King