this is a thought ive had for awhile and its about the armbands everyone has had tied to them in s4 when the jeagerists take over.
first, theres the white armbands. the one of those who are jeagerists. white can symbolise purity, innocence and is usually used to depict people who are in the right. 'purity' is a major part of this because it shows their support for the euthanasia plan that zeke and eren have. by having everyone stop reproducing, you get rid of the 'unpure' people, the subjects of ymir, who can turn into titans.
then, there is the people with red armbands. military prisoners who hadnt drunk the wine. the colour red can be used to denote anger and danger. though, it can also symbolise love and passion. but i would say in this context its more of the negative emotions associated with red. the jeagerists have to have caution around those with these armbands because they dont have leverage over them. red is easily distingushable from both white and black, making them easier to keep an eye on.
finally the black armbands of those who had drunk the wine. black is used to typically portray evil, the people who didnt want to conform to the euthanasia plan but had no choice. black can also represent death, in this context the death of the militarys free will as they had to submit or they could be turned into a titan at any second.
