Blue: (snare/bass, percussion) 

 I headcanon him to be represented by percussion and/ or battery (the marching part of percussion). This is because the percussion is often the driving force in music, the heartbeat of the song pushing the tempo forward. In an ensemble, percussion is often used in tandem with the brass section (keep this in mind for later!! <3). In a marching band, the percussion guides steps and cues, having a percussion section going too slow or going too fast can result in a song that feels dragged or sloppy. I feel as though this mimics Blue’s role in the colors. His energy drives them forward to action and battle, but should this energy get out of hand, it affects the whole group, dragging them along and leaving little room for adaptation and teamwork. 

Green: (trumpet, brass) 

I see green as the brass section!! For some background, heroes are often associated with brass fanfare, this dates back well into the nineteenth century and hunting calls. However, for more recent associations, trumpet fanfare is popular to represent a paragon and hero (superman's theme anyone?) however, its paramount that the brass have *balance.* If the brass is too loud, it can drown out the softer woodwinds and strings. If it's too quiet, the music may not have a backbone, as melody, the main idea of a song, is often found in the brass section. Again, I think this is similar to Green’s role.  In the manga, initially, green sees himself as the original link, the hero of the story. He, in a way, is drowning out the rest of the colors. As the manga goes on, he learns teamwork, and learns to get along and let the others have their time in the spotlight. 

Red: (clarinet, woodwinds)

I believe the woodwinds would be a great fit for Red!! The woodwinds are often used to associate things as small or harmless. But we all know Red is far from that. The woodwinds can be used in a variety of ways, they can be light and airy like the flute and piccolo, but they can be powerful and strong like the bari sax and bass clarinet. Woodwinds are often used to add counter melody or flavor to the main melody, and complement and go well with other instruments, similar to Red! Red gets along with others more than the other colors, and while he may not be at the forefront or have a need to lead, his influence cannot go unseen. Without him, the group would be lacking depth and grounding.

Violet: (violin, strings)

Last but certainly not least, we have vio!! Who I headcanon to be the string section!! The strings have many *many* associations, but the most common ones are class, melancholy, and emotion. Vio, more than the other colors, has shown to be considered more well read, he’s cunning and adaptive, and it's those very traits that lead to his betrayal of shadow, and the guilt and grief that followed. The strings are also adaptive, and can be bass, tenor, alto, and soprano, they can lead or fall into the background, whatever the music requires. However, it's important for the rest of the instruments to *listen* for the strings, as they are easily drowned out. 

While separated, the colors are mainly represented by a single instrument, (the first instrument listed after their names above). I choose higher register instruments to represent fours youth and size, but not the highest register instruments available because while he is young, he is mature. He’s been through multiple adventures, and has had to grow up very quickly. 

With that being said, it's time for shadow!! 

Shadow: (bagpipes)

oKAY, I meme the bagpipes a lot, but there's an interesting fact and association with the bagpipes. Many composers have noted that the bagpipes go especially well with the string and orchestra! (it's all coming together) The bagpipes are rarely utilized in modern music, and thus when they are used, the music may sound strange and otherworldly. They represent the unknown! I feel as though this fits shadow, as he indeed is otherworldly. And along these same lines, as a villain, shadows motives come from a place of misunderstanding and *not knowing* how to act. 

Now for some miscellaneous musical ideas!!

Before pulling the four swords, Four’s motif would be well blended and simple. A basic build off a four note chord, like the cmaj7 chord!! The cmaj7 chord is an fairly upbeat chord with with just a hint of sadness

Immediately after pulling the four sword, fours theme would divide into four separate parts, each using a color’s instrument for the melody of that section and each based off of a note from the cmaj7 chord. Each time one of the colors is featured or doing something noteworthy, their instrument and “note” is played. (this is just done quite often!! Look up “azula’s chime” or “peter and the wolf!!”) 

As Four masters the four sword, his theme slowly stitches itself back together, but it still has recognizable sections to it, and those four instruments alternate for the melody!!

Shadow’s theme would be fours theme reversed and played on the bagpipes!! That way he would still have a connection to four, and be a part of him, while still being unique and his own person! I also think that while evil, his theme would be in a C#dim7 key and based on that chord, but as he switches to the side of good, his theme would become less ominous and gradually change to the cmaj7 chord like fours.

Also representing four before the four sword, I think a staccato beat would be best to represent the fun, upbeat, and exciting nature of his adventure with the minish, but as time goes on, the staccato beat morphed into a steady beating bassline, like a heartbeat. 

Links: 

The C#dim7 chord

https://www.youtube.com/watch?v=E7WKalP8Exk

The Cmaj7 chord

https://www.youtube.com/watch?v=3mKy-DfW0gE

Azula’s Chime

https://www.youtube.com/watch?v=dIanHWbmKiQ

Peter and the Wolf 

https://www.youtube.com/watch?v=Va8Uz6MoKLg

Example of strings and bagpipes 

https://www.youtube.com/watch?v=XeRR6O030v8

Examples of bagpipes being used to represent the unknown and musical growth and how themes can change

https://www.youtube.com/watch?v=BVp_KdNQaRU&list=PL4D48F7B301C79783&index=3