red for luffy as a passionate,energetic and motivated person!
blue ford katakuri as a “Cool, Calm and Collected” guy!
while the red + blue :
purple
Sparks Imagination
Purple inspires us to divulge our innermost thoughts. As a result, we gain a more profound understanding of who we are. This level of imagination gives way to spiritual growth and guidance. Many enjoy the otherworldly impact that purple has on them. The blue hues that are found in purple are responsible for the spiritual intuition that it provokes. In essence, the color purple encourages the mind, body, and soul to live in harmony
their fight happens in the Mirro-World as the mirror symbolize self-awareness : both of them getting self-aware about Their flaws!
- Katakuri had all the power in his arsenal but cursed with being the "perfect man" ( even the FS represents his personality : he wants to protect his family so bad that he wants to know what is happening in advance and stop it in the best way!) while he had to look at the free luffy who is perfect at being imperfect
- Luffy had to control his emotions and excitement and in another word growing up and not being that careless boy anymore in a very painfull way