Diablo's death in Suicide Squad comics was a result of a powerful confrontation with a major villain. His powers were overwhelmed, leading to his demise.
Harley Quinn might get really into it. She has a wild and unpredictable personality. She could start to role - play some of the scenarios from the fanfiction in real life, much to the confusion or amusement of the other Squad members. It would be in - character for her to embrace this strange new view of their world.
Well, El Diablo's back story is quite complex. He grew up in a harsh environment, facing numerous challenges and hardships. This led him to develop a certain mindset and eventually acquire his unique abilities under extraordinary circumstances.