Souls

Souls are the very incarnations of sentience within beings - one of Totality's very few constants. The soul always exists in something in one way or another, laying beneath the visible, physical world, enacting their wills in a space below space, and in a time beside time.

Let's Go Deeper.
Souls are the sources of life for nearly all thinking beings (Depending on the rules of some abstract realms, a being may exist without a soul behind it). A soul is composed of Soft Energy, meaning that it is incorporeal, and unable to be influenced by any physical force (via Hard Energy). That being said, a soul can be influenced by a stronger soul, also acting through Soft Energy. Additionally, a soul using Soft Energy could potentially influence the physical world, crossing over into a Hard Energy state temporarily.

Depending on the realm, a soul may require a host, often in the form of a physical body which can uniquely influence Soft Energy, in some way. For instance, the human brain is an adequate host, allowing for unique souls to survive through it. Without a host, a weak soul may dissipate into its component energies, and be recycled and reused by other, more powerful souls - even picked up and added to a soul’s total energy without the receiving soul’s awareness.

Of course, more powerful souls could hold themselves together without the need for a host, though it is still a form of Soft Energy and cannot interact with the physical world. On Earth, this can potentially be interpreted as a ghost.

And finally, the most powerful souls (of which few exist on Earth) can create its own energy (Soft or Hard), and even create its own physical body, through which it is able to express itself more easily.

When a soul is so deeply ingrained into its body, it can begin to truly believe that its body and itself are inseparable. With this comes the issue of reproduction, which some species do to increase their numbers. A soul can split itself to create a new, thinking consciousness quite easily, with energy to spare. As souls usually are able to generate their own Soft Energy, the parent soul or souls can split off small parts of themselves, and allow the small parts to grow into their own identity. Alternatively, the species can also create a new soul from scratch, using spare Soft Energy.

I’ll leave it to your imagination to decide which method human souls use. Of course, there are other methods, as well.