Shigadabi
In an AU where neither of then has any emotional intelligence but both have sexual drives. So they fuck without realizing that they are falling for one another, and the only way they can express their wants is the way that the sex turns slowly sweeter and sweeter. First they remain in bed for a bit longer, then clean each other up, then just sleep in the bed cause of exhaustion and them cuddle. (Cause of exhaustion and they only do it when they are sure the other is "asleep" and then claim it was an accident.)
And it slowly turns to the point where they don't even do it, but just undress and lay in bed together cuddled up.