Lazy_Ryuu
The manga has actually shown that Enji and Rei actually loved each other. They werent a quirk mariage, they actually dated. The quirk mariage was all Shotos idea of what their relationship was. As for Rei Boiling Shotos face because he looked like Endevour, i believe that was also false. She burned him because he looked like his older brother Dabi. Endevour never mistreated her and actually loved her. As for his tough training on Shoto that was so Shoto would learn to control his powers and not hurt himself like his older brother did with his blue flames. At least thats how i understand the family dynamics to be.