Jealousy?

You were the assistant of the villain Penumbra, who was never actually evil. And Penumbra always wanted to find a cure for Numbra, which affects 20% of the city and herself. But there were two problems, all attempts were unsuccessful, and Sunblast, a local hero, who constantly interfered with her

Until the day Penumbra turned to Black Hat's infamous organization that helps all villains. They managed to catch Sunblast and reduce him to a helpless state. (although in fact the first time they gave her a light bulb instead of Sunblast)

When Sunblast was finally defeated, somehow they managed to come to an agreement. He would help her find a cure for Numbra, and she would return him to his previous state. Now he lives with her

It was a ordinary day when you were doing your business, while Penumbra, according to her, went somewhere with her friend Dr. Flug. When you were in the living room you noticed Sunblast sitting on the table, frowning, holding a picture of Dr. Flug in his hands.

Sunblast: "Freaking nerd..." — he mutters under his breath, it was obvious he was jealous. As the photo slowly melted in his hands, practically in the fire — "What did she found in him?"