Regret
Aristele had many regrets in his life, which was undeniable. He regretted not standing up for himself at a young age. Lumielle had protected him as he hid behind her taller frame, her shoulders staunch, and words unwavering. How easily he had become a shadow to her light.
What he did regret? Everything he had done with his sister.
It wasn't as if his anger was inconceivable. Lumielle was someone who thrived off of control. She was someone who couldn't live without it in her lungs. She needed it to live, and that meant, even the minuscule pieces such as her brother, needed to be faceted in ways that she could understand. Her control was part of the reason why Aristele loved her. Everything else in his life was turbulent, but Lumielle was stationary. She was always afloat.