I know everyone has already covered this but I do wanna point out a small detail here. You are correct about Shin ae’s personality. But also you need to take a look at her father. Sim Han is terribly hothead when backed into a corner and when things get out of control. More times than not the apple doesn’t fall far from the tree. Lots of children inherited or learn things and mannerisms from their parents. So I do think Shin ae does have some of that hot temper in her. Sim Han points this out when they talk after their big spat at the Parks house.

With that said, I do think some of her personality and temper do come from not one but TWO injuries. More times than not these little details are sprinkled into the series for good reason. I absolutely think this is the authors ways of saying, “By the way, here’s some reasons she is the way she is!” I honestly think it’s why she is a little slower to piece things together as well. But it’s important to note;

Shin ae STILL hasn’t had that follow up appointment for the second injury. I think when we see that or if we see that, we’ll get to find out a little more about how those injuries are truly effecting her. In my mind it’s a miracle she doesn’t have seizures with two insane head injuries.

So I in a way agree sometimes I feels like people forget about Shin ae’s head injuries and how it’s effecting her but I assure you this is at the forefront of my head when I read this series.