How can a creature caught between realms feed on mortal prey?

[Erebus]

a witch can use a ritual which aborts her pregnancy and uses the remains of the resonant soul to form a botchling. These pitiful creatures are malformed, misshapen fetuses made with half a soul. They are caught in an intangible state between life and death which float and hover over their creator, and serve as spies and counselors. A botchling is bound to the witch and cannot stray more than 100 yards from them. They can turn invisible at will and cannot be affected by anything on the physical plane. When the witch connected to a botchling dies, the creature loses its tether and becomes unbound to the mortal realm, leaving them in limbo. Caught between a state of life and death for an eternity, these pitiful creatures cannot interact with the mortal world, nor pass on into the next life to know peace.

Over time, a botchling develops a hatred for all life and morphs into a lamia. These are creatures that prey on both unborn souls and the children of unsuspecting parents. As they were prevented from being born into the world by their witch, their child-like mentality and anger causes them to lash out and take vengeance for their state. They seek to cause suffering to other mothers by killing their own children. Their victims are specific to kids below puberty. The problem is that these beings are still caught in the state of limbo. How could I design this creature to be unable to interact with anything on the mortal plane, yet still be able to feed on their prey?

 

[ShadeZ]

If they are spirit-based couldn't they interact with human souls (assuming your humans have souls)? Also maybe check out the demogorgons in stranger things as this sounds very similar. You could also however make it so that they can affect their prey only.

 

[Yora]

I would them have drain their targets souls. Since that is also spiritual energh they can interact with it.

 

[K.S. Crooks]

Could they feed off of negative energy created by hurtful thoughts and deeds or from suffering. Feeding on negative auras.

 

[Kalessin]

Where'd you get the concept? Your own mind? I Googled botchlings and found an entry on the Witcher wiki that made no mention of the limitation you're dealing with here.

The answer, with respect to a specific version you're inventing, seems to be wrapped up in the nature of magic itself within the story. Witches seem to be able to interact with things outside the mortal plane. Why can't something outside the mortal plane interact with something inside of it? To what degree is a mortal connected to the spiritual side of things?

Yora said it a lot more efficiently than I did, and I'll second their sentiment. Children have souls in this world, presumably. To what degree does a soul in this story represent a link to the immortal plane?

 

[WooHooMan]

Isn’t it pretty common for demons to exist on a spiritual plane but prey on beings in the mortal plane?
Maybe the botchling (I like the name by the way) can operate through possession, curses and whatever it is that demons tend to do.
I think it would be cool and interesting if a botchling hunting its prey would resemble the first half of the Exorcist where the child character is slowly being “eaten away” by the demon.
And I’m assuming this story of yours is supposed to be more of a horror story since this is some grizzly stuff you’re talking about.