Soojin doesnreally show her affection towards the younger, but of course she shows it off cam  by spoiling the maknae, cooking for her and specially the stares.

Soojin rarely opens up but except for one no kidding  almost all of her secrets are known but of course by shuhua, She never really tells lies to the younger, she tells everything, that's how much she trust shuhua. 

Last, Soojin rarely cries, she just lets it out when its because of happiness or the opposite of that, soojin is like a book, but hard to understand, Memories is the only thing shuhua has last gave.