I used the logos Valve created for their combat-themed hat simulator Team Fortress 2 as an inspiration. While some of the symbols (flying coffee cup for Elly, train for John, trumpet for Phil, null symbol for Georgia) are obvious, some get a bit obscure.
As by way of example, Mike's symbol came to me because he impresses me as being a crappy son, a crappy brother, a crappy friend, a crappy boy friend, a crappy husband, a crappy father, a crappy author....this means that the best symbol for him is a toilet. This is also why I used a plunger for Mira. How else do you clean a clogged toilet of a man like him?
As for the different colors, if someone is being a jerk, they're blue because blue attacks; if they're absorbing jerkishness, they're the red that defends.