My cousin's kid asked about the colours (she's 16, it was a 'is this a thing, you did media' question) and yes, there are reasons why the characters, specifically the main 5 have the colours they have. Part of the main 5's colours did stem from Tumblr's choice of colour text options, I can't really understand html stuff easily, I tend to stick with plain-text editors.
TL;DR: Colour Theory, yay, It's been 7-8 years since I was in college, wow I feel old. Now pls read it I put 2 hours into writing this.
Angel
Angel is red because red, as we learn in media studies, is often used to represent characters who are either bold and brave, or emotional and hotheaded, I wanted Angel (I should really be calling him Ángel) to be this sort-of headstrong self-titled leader, the kind of man who people don't know if he's really in the right head-space to be the leader, he's got this sort-of 'righteous fire' in his heart 'cause he thinks the organisation they work for is ultimately good.
March
March is blue, 'cause blue (I'm one again using my college research from like 7-8 years ago) is the tranquil one, but because blue is the colour of the ocean it holds depth, and anger, and I wanted March to be the kind of guy who has many, many layers to his emotions, he always seems calm, always looks happy, but behind closed doors he's a deeply closed off guy trying to make sure everyone's happy before he is.
Sid
Sid is orange. Orange is a weird colour to pick for a security agent. But, Sid, he's an orange guy (not in a Trump-ian way, Sid would never get that level of spray tan). In colour theory and media, we are taught that Orange is the up-beat energetic colour (hence Mikey in all versions of TMNT), but it's also used in a biblical way to represent gluttony, and what does Sid want, he wants what he can't have, he wants Church is a very sinful way, and he gets so jealous, Sid's guilty of sins, but Sid hides this with humour, and with his no-nonsense energy.
Poe
Poe's green 'cause aliens are green, lol. I'm kidding, but also a lil bit yeah, green can be used to represent inexperience (if you've ever heard a wrestler described as green, it's usually cause they're young or new), but green can also be youthful and vigorous, and Poe is the newest, not the youngest, member of S.P.O out of the main 5, so he's the 'greenest' guy they have. Poe, alongside Church is where we start to see the colour themes get played with a bit, Poe's still relatively new at the start of the story, so he has yet to fill his very green shoes, metaphorically speaking.
Church
Church is a woman, yes, but she isn't pink because of her feminine nature. Church gets pink as she's innocent to the world, she's been with S.P.O the longest, not by choice, she's never really had a 'life' outside of the organisation, pink is also used for those with a delicate nature, and due to Church's psychic powers, she can't be skin-on-skin with anyone, so she's very light-handed with what she touches, the smallest touch of a person (including post-mortem) and she's aware of things she (or they) might not want her to know. Church is also an example of inverting colour choices, as her association with pink is in some ways, ironic, she's not a healthy woman, nor is she particularly romantic, she's not aromantic, she just doesn't really understand how flirting works, nor a 'relationship' (she was raised in a [REDACTED], fine, S.P.O, her family was like Charles Manson)
“There is a word for places such as the one we find ourselves in now,” Angel had whispered, “Orphic.”
Sure, it had resonance, any word would out of the mouth of Ezekiel Angel, self-titled leader of the group and the only one still standing after hours of ‘trekking’ (as he would call it, at least).
“There’s a word for what you are, Sir, ‘Deluded’.” Sid smirks, looking towards he others to see if they approve.
They do, each of the three nodding with a small grin, holding back laughter as Angel scowls.
“Yes, but ‘Orphic’ has a ring to it, Sid.”
[101 Words, good start in my own opinion, but I do want feedback]
