does anyone know what the individual colors above the men's heads mean?

Yea it's a spoiler though, still wanna know?

Spoiler
Red= romantic love
Black= obsessive love
Orange= first love
Pink= familial love
Purple= imperfect love

spoiler











isnt orange lust cus i heard ppl saying derrick said in the novel he wants penelope as a wife rather than a sister

That's true it can be interpreted like this too. He didn't really realise it almost till the end, that what he felt for her wasn't siblings love. He was a trash from the beginning but he was also very slow with understanding his weird desires and was confused. In my opinion first love is better describing the whole nuance between them. But yeah he wished to put her in the cage and own her so lust works as well. I kinda feel like it's included in first love haha but tbh lust is more like physical aspect and for him it was more like psychological need... But both types are correct I think.

what does imperfect love mean?

Hm that it's lacking I guess, like he doubts and puts her to test. It's flawed in many aspects.