Fan Created Offspring:
Term used to refer to any OC who is a kid of one or more characters, often referred to as fankid, shipkid or lovechild.

Character Fusion:
Term used to refer to any character that is a combination of 2 or more characters, In the UTMV fandom, the term Combos is used instead.

Basic Monster biology

Monsters' "blood" is known as energy; it comes from their SOUL and gives their bodies form. The energy inside their bodies is referred to as "passive energy" (P); the energy they use to create their magic attacks is known as "active energy" (A).

Monsters can activate their energy both voluntarily and involuntarily if the body deems it necessary; monsters in dangerous situations, younger monsters, and those who have strong stress reactions and/or suffer from mental health disorders are more prone to activating it unwillingly.

ESC traits

Patients with ECS have a weaker SOUL than the average monster; this is due to many reasons, usually from being underdeveloped in formation. A weaker SOUL might look smaller and/or have cracks in it.

The weakness of it makes their energy unbalanced, trying to generate more energy to compensate, and ending up congested in certain parts of the body (usually arms and legs). This causes harm to the patient and might even cause death if it goes untreated.