Fusion is an ability that is considered common or extremely rare depending on the way it is used in certain beings. As opposed to other skills, it is an ability with flexible capabilities: whereas only ghost beings can have element-based powers (such as Cryokinesis or Pyrokinesis), fusion is something that ghost and non-ghost beings are able to perform.
Fusion, in general, is the process by which two or more specialty individuals combine their physical or spiritual forms to create an amalgamation (AKA "fusion-type") classified as one solid form. There are different types that can occur and their classification varies between individuals involved. Depending on the compatibility of individuals composed in a fusion and their general personality traits, it is possible to become "lost" if fused for too long, which is why it fusion (as an ability) is best left only to highly-skilled beings.
This is the full vocabulary list that spans across general media (with slight variances depending on other people's usage).
- Type -- The specific classification for a fusion whether they are reoccurring or singular.
- Lost -- To become "lost" means that individuals within any given fusion can lose their individuality and completely mesh with their partner/partners. When this occurs, it creates an entirely unique personality that is defined as the "true fusion." Depending on the individuals' compatibility and personalities, this "true fusion personality" can either be harmonious and enjoyable (for both the fusion and their components) or chaotic and destructive (most likely stemmed from the pain felt by the fusion's internal components). To avoid being "lost" to a fusion, members engaging in the ability are strongly advised not to remain fused for too long.
The rate of which a fusion-type has been known to occur.
- Frequent -- Can be accomplished by most types of beings with practice and good core relationships.
- Somewhat Frequent -- Describes any ghost's relationship(s) with the halfas, of which there are few. According to mainstream media, there are only three known halfas (Danny, Dani, and Vlad).
- Rare -- Can be accomplished by some basic and/or more powerful types of beings with practice and good core relationships.
- Extremely Rare -- Can be accomplished by well-versed basic and/or more powerful beings with practice and good core relationships.
- Unique -- Can only be accomplished through miraculous circumstances with virtually no chance of being reproduced by other individuals.
Pure Fusion Types
This list of fusion types specifically pertains to ghost-ghost fusion.
- Basic -- A fusion form composed of two beings, which is considered a frequent composition. Stability odds are generally 1:2.
- Complex -- A fusion form composed of three beings, which is considered a rare composition. Stability odds are generally 1:3.
- Multifaceted -- A fusion form composed of four beings, which is considered an extremely rare composition. Stability odds are generally 1:4 (depending on the involved individuals’ level(s) of compatibility).
- Extremely Multifaceted (AKA Cluster) -- A fusion form composed of five or more beings, which is considered an extremely rare composition (and extremely dangerous). Stability odds are generally 1:5 - ∞.
Impure Fusion Types
This list specifically pertains to ghost-mortal, halfa-halfa, halfa-ghost, or other non-ghost-ghost fusion types.
- Mortal -- A fusion form composed of a single human being with a single ghost being, which can only exist within the mortal’s physical form under near-death pretenses where the ghost being is fused with the human to sustain their life force in a symbiotic relationship. In return, the ghost being can experience all mortal senses as their human counterpart continues to exist; stability odds are 1:1. This is considered a unique composition.
- Split -- A fusion form composed of a single mortal being with a single ghost being, which is only accomplished by both individuals being charged with a surge of ectoplasmic energy. This is considered an extremely rare (if not a unique) composition. Stability odds are 1:1.
- Simple -- A fusion form composed of a single Halfa being with a single ghost being while the Halfa is in their human form. The ghost being can overtake the Halfa and control their physical form with their ghost-half already infused while the human-half is released of their form, including access to their own ghost powers. It is considered an extremely rare if not a unique composition. Stability odds are generally 1:2.
- Flexible -- A fusion form composed of a single Halfa being with a single ghost being, which combines the Halfa’s human- and ghost-halves with their ghost partner. It is considered a somewhat frequent composition. Stability odds are generally 1:3.
- Freelance -- A fusion form composed of a single Halfa being with a single mortal being, which combines more of the human forms of both beings and a lesser amount of the Halfa’s ghost form; stability odds are generally 1:3. This is considered a rare composition.
- Vibrant -- A fusion form composed of two Halfa beings, which combines both human- and ghost-halves from each individual. It is considered an extremely rare composition. Stability odds are generally 1:2 - 1:4.
- Dynamic -- A fusion form composed of three Halfa beings, which combines the human- and ghost-halves of each individual. It is considered an extremely rare composition. Stability odds are generally 1:3 - 1:6.
- Intense -- A fusion form composed of one Halfa being and two ghost beings, which is considered an extremely rare composition. Stability odds are generally 1:3 - 1:4.
- Cosmic -- A fusion form composed of two Halfa beings and a single ghost being, which is considered an extremely rare composition. Stability odds are generally 1:3 - 1:5.
- Systematic -- A fusion form composed of two mechanical ghost beings that combines their technological interfacing, which is considered a rare composition. Stability odds are generally 1:2. NOTE: It is not considered a “true” fusion because there is no consistency in organic form, unlike other ghost or non-ghost fusion types.
There are only three known examples of fusion portrayed in the original show -- two of which occur in "The Ultimate Enemy," although one is debatably not a "true" fusion, and the first appearing in "Splitting Images."
- "Sidney Fenton" -- As opposed to the popular misconception that Sidney simply possessed Danny, their inter-correlation is actually an example of a Simple fusion-type. While Sidney managed to "kick" Danny out of his body, Danny Phantom remained fused with said physical body, which allowed Sidney full control over the two. Their fusion is more primitive in nature when compared to the relationships between Skulktech 9.9 and Dan Phantom in later episodes. However, this fusion-type is unique because it only occurred between Danny and Sidney once and was not attempted by anyone (either with Danny or Sidney) through the duration of the series.
- Skulktech 9.9 -- A Systematic fusion-type between Skulker and Technus, which only existed in the alternate timeline in which Danny's family and friends were tragically killed. They no longer exist in reality. They make a cameo appearance in "Phantom Planet" as one of many ghosts that help turn the earth intangible to prevent total destruction by a massive asteroid, although the timeline in which they existed was destroyed, so their appearance is nonsensical.
- Dan Phantom -- The infamous evil Basic fusion-type between Danny and Vlad's ghost-halves. Created on accident, they became a destructive, chaotic individual and sought to bring forth the events that caused the tragic death of young Danny's family and friends in order to ensure his own existence in the actual timeline. Because of Clockwork's interference before Danny's time ran out, Dan is last seen being trapped in the Fenton Thermos under Clockwork's guard, which lies outside the realm of time.
Within the Danny Phantom: Spectral Connections series, fusion is an increasingly common ability exhibited by some characters, of which popularity steadily grows by Danny Phantom's influence. As a main prerogative throughout the series, Danny must understand and master fusion as a skill if he is to defeat some of his greatest foes in the future. More to be revealed later!