Hatred

Hatred has usually be seen as an emotion however, it originally originated from one of the dark ones who are said to be led by one of Cthulhu's children which can be harnessed in the form of energy which itself has great affinity for those who are more easily drawn into the dark side which is said to originate from Cthulhu's dark powers.

Summoning
It is said by some groups that Cthulhu itself can actually be summoned forth if a sufficient portion of hatred, energy and data (along with a secret ingredient which is kept highly secret) is available along with being harnessed in the correct way by one who has a significant affinity with Cthulhu itself rather than, any ordinary being which makes such beings extremely rare with the quantity of the resources needed being so incredibly large.

As one alien described before, even if an entire universe was filled completely with hatred, it would still not be sufficient for the summoning ritual to bring forth Cthulhu although, a large number of organisations are interested in using it's powers for their own ends despite it being a being so powerful that, it listens to no one.

Power Source
Beings with an affinity with hatred are capable of using it as a power source with which they can replenish themselves and even shape it into the form of weapons which they use with them being able to use their own hatred for this along with the hatred of other beings in the area which can be extremely useful when the area has an incredibly high level of hatred (in comparison to most other areas) as the power supply increases vastly.

Theories
Recently, an alien proposed an alternate theory to the current understanding of hatred in general with hatred itself originally being a mere emotion however, it evolved into something much more darker and powerful when an omniversal spell was cast by one of the Dark Ones leading to it becoming a force that impacts all the beings including ones that have evolved beyond emotions.

The source of hatred as a power being by those with an affinity towards the Dark Ones due to them being able to manifest hatred via a reality warp from themselves and those around them with intense hatred as the art of reality warping is where one makes thoughts reality however, emotions tend not to fall under thoughts.

As one gains a stronger affinity towards hatred, they evolve new ways to manifest it with the possibilities potentially being limitless however, this field is currently under pretty heavy research and thus, will take time to research better results.