@Jon-Anderson I like your idea and this scene makes me laugh. Regarding your questions: (1) Your concept of spreading color as a metaphor for the added flavor that the octopus is bringing to the chef's cooking is really cool, but I think the hatching detracts from that effect. I feel that focusing on the color gradually turning to b/w or more subdued values at the edges, without the hatching, would communicate your message better; (2) The color palette works for me. I think if you keep to those colors, then add some light and shade values from the light sources in the room, everything may tie together.
Extra note: that silhouette in the door behind the main figures is very mysterious and pulls me away from the important action in the kitchen. Perhaps if you added another silhouette in the other door window, as if they two figures out there were just talking, it would feel less distracting.