Hastur comes to Earth
As the war between Good And Evil and the Old Ones was coming to an end, a cunning new plan was hatched that the Old Ones hoped would turn the war in their favour. The Old Ones sent one of their own, Hastur, to Earth to develop weapons to defeat the forces of Good And Evil.
Setting up his base on a remote island, Hastur began to develop the aforementioned weapons to aid in the war efforts of the Old Ones.
Among the weapons that Hastur developed for the Old Ones were the forces that would later became known as the Hollow and the Nothing. Both these weapons were deployed had had devastating effects on the forces of Good And Evil.
However, by this point, it was still too late to turn the tide of the war in the Old Ones favour. The Old Ones were sealed up in their empty dimension.
The Hollow and Nothing were both taken by the forces of Good And Evil as spoils of war. The Charmed Ones would one day have encounters with both these forces, while never knowing of their true origins.
Hastur goes into suspended animation
The forces of Good And Evil then sank Hastur's Island, so no one could find it.
However, Hastur had already planned ahead for that eventuality. Before the island was sunk, Hastur had placed himself in a state of suspended animation, in a sarcophagus, located inside a huge temple.
There he would remain for the next 5000 years.
Hastur's black stone
It was from some writings transcribed from that stone that Rex Buckland and Hannah Webster first learned of Hastur's existence.
Hastur is awakened
In 2017, Johanna Martense and Herbert West travelled to Hastur's island, having learned its location from the Mi-go in the Himalayas. After using her magic to raise the island, Johanna and West began their attempt to awaken Hastur from his millennia long sleep.
Despite the presence of Rex Buckland, Hannah Webster, and Randolph Carter, Johanna and West managed to transport Hastur away from the island and succeeded in awakening him.
Once Hastur was awake, Johanna and West vowed to do his bidding. Their ultimate goal, to free the Old Ones from their empty dimension prison, was now one step closer.
Matthew Tate scheme
Not long after, Hastur, Johanna Martense, and Herbert West managed to capture a Demon named Zathan, in order to get information on Rex and Hannah. Zathan told them about the time that he, under the orders of the Source, had brought Melinda Warren's locket, containing Matthew Tate, to Rex and Hannah in 1998, and the subsequent events.
Intrigued, Hastur sent Johanna and West to steal the locket from the Witchcraft Museum, in Salem, and bring it back to him. Using his powers, Hastur managed to track down a descendant of Melinda Warren that no one else knew about, and sent Herbert West to her with the locket, from which West was able to procure Matthew's release.
Once Matthew was released, Hastur posed as the Source, in order to trick Matthew into obeying his orders, namely going after Rex and Hannah, to keep them distracted. For a while, the trick worked, until Rex and Hannah managed to convince Matthew of the truth, that he was serving an imposter.
Angry, Matthew confronted Hastur, and demanded to know his identity. Hastur obliged, showing Matthew his face, which ended up driving Matthew permanently insane.
Rex and Hannah Chronicles Story No. 45: The Siege Of Fort Albert
Rex and Hannah Chronicles Story No. 46: The Island
Rex and Hannah Chronicles No. 47: Revenge From The Past