Ethan perceived Krystal as a younger sister. He tried his best to look after her whenever he could.

He saved her by chance that year, but she ended up pestering him!

In the past, she insisted on going with him for his missions. He assumed that the young lady yearned for real-life experience to prepare herself for promotion.

On top of that, she indeed donated her blood to him during emergencies. Thus, he intended to help her out.

As she grew older, her feelings for him became more apparent.