Theonite resonance is a spike of energy that comes from strong constriction of Theonite. Several spots in New Meridian have been mentioned to contain Theonite resonance. However, the biggest source comes from the Skullgirl herself, suggesting that Theonite either originates from the Skullgirl or that the Skullgirl uses a large amount of Theonite when utilizing her abilities.
- Parasites and Living Weapons are said to be created using Theonite. Some are mentioned to use or feed off Theonite to strengthen their powers.
- Isaac has been using shards of a unique type of Theonite he discovered in his search to time travel.
- Anti-Skullgirl Lab 6 specialized in Theonite research, to discover the full capabilities of the material.
- Dr. Avian used Theonite to balance out Peacock and prevent soul contamination, a mental corruption that occurs in people possessing multiple (synthetic or natural) Parasites.
- Theonite has a big involvement with the Skullgirl. Using a Theonite Resonance Detector, Peacock and her crew were able to close in on the Skullgirl.
- In the alternative ending for Valentine, she said there could have been a way to seal off the "Theonic" energy of the Skull Heart, meaning that the Skull Heart eventually is related to "Theon" in a way.
- According to Eliza, Parasites were known as Theons, which may be the in-verse origin of the name of the material.