Every time I see ABO fanfic I'm like... filled with love for how weird human beings are. It's so endearing. I sincerely love that for no reason other than wanting to, people spend hundreds of hours of time writing about what it would be like if humans went into heat. I love that it took off as an actual AU with defined rules despite not being in mainstream media at all. People discussed it amongst themselves and came to consensus about this invented kink. Human beings, man.