What's a rakshasa? I've heard the word before but I don't know what it means.

In Hinduism, rakshasas are a race of malignant demons. They have great powers such as flight, speed, super strength, the ability to spit fire, shape-shift, invisibility, and the power to create illusions. The males are called "rakshasa". The females are called "rakshasis". Rakshasas, most of the time, were malevolent and caused atrocities such as eating humans, disrupting sacred ceremonies, sabotaging the works and teachings of gurus (spiritual teachers) and leading people to wrongdoings. In India, vampires are considered rakshasas because some rakshasa species drink human blood. Not all rakshasas are evil; however, some have actually used their powers on the side of heroes.

The realm of rakshasas are part of the six realms of the wheel of Samsara. The realms are as follows:

The realm of the devas (gods)
The realm of the asuras/ashuras (titans)
The realm of the rakshasas (demons)
The realm of the pretas (hungry ghosts)
The realm of the humans
The realm of the animals (which also includes plants and trees)

The realm of the rakshasas is one of the worst realities to exist in. It is said that people who live multiple lifetimes of hatred, rage, and violence end up reincarnating as rakshasas and the only way to exist this state of being is by learning not to retaliate against wrongdoers, to make an effort into not resorting to violence, and controlling one's rage. The realm of the rakshasas is also known as part of the buddhist hells. It is also believed that people who are vindictive and easily volatile have the headspace of a rakshasa.

In Sanskrit, asuras (also spelled ashuras) is also translated as demons, but they are not the same. Asuras are more like titans than monstrous demons. Asuras live in the heavenly realms (the realm of the devas). Like the avatar I'm using, the horse-heads (Hayagriva in Sanskrit) are asuras who once raged war against the devas. The reason why is because the devas once promised the asuras higher knowledge but then for some reason broke their promise to the asuras refusing them the knowledge. My main character (Mira) is an asura (ashura) in my story. Some people on the internet easily confuse asuras and rakshasas. Asuras are also known as the feminine energy beings and the devas are the masculine energy beings. Deva energy is light and orderly. Asura energy is dark and chaotic.

Rakshasa energy is also dark but not like asura energy. Asura energy is natural chaos which has its purpose in nature. In order for new things to come old things go. Take forest fires for example. Natural forest fires can sometimes result from lightning hitting tall trees. Parts of the forest burn down but it is replaced by new growth. Rakshasa energy is corrupt energy. Someone with animosity might commit an act of arson to destroy a building is fueled by rakshasa energy.

Having a rakshasa headspace is also illustrated in a Buddhist story. Once there was a military general who wanted to question a Buddhist monk on the existence of heaven and hell. He approached the monk (who was calmly meditating) and angrily demanded what was hell. The monk replied, "Sir, you are in hell right now." The general calmed himself down and next asked quietly what was heaven. The monk smiled and replied, "Ah, now you are in heaven." A calm mind is the heavenly (and preferred) mindset.

I'm glad you asked the question! If you have any more questions, just ask and I'll answer as soon as I can!

Interesting. In a JRPG series I play, one of the characters is nicknamed the golden Rakshasa. Now I know why. Not like I didn't have an idea though, she's pretty much one of the most badass characters in the game.