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[Hyuk] Tteonaji mara [Hongbin] (nareul tteonara)
[Hyuk] Neoreul saranghae [Hongbin] (ani nega sirheo)
[N] Jikil and haideu da naya na domangchijima
The lines from Hyuk and Hongbin are trying to explain the "Jekyll" and 'Hyde' point of views.
While Hyuk is saying "Don't leave me (Tteonaji mara)" and "I love you (Neoreul saranghae)", Hongbin comes in and adds on "Leave me (Nareul tteonara)" and "I hate you (Ani- nega sirheo)" This is expessing that Hyuk is "Jekyll" and Hongbin is "Hyde".
N's line after explains that they are both Jekyll and Hyde and they don't want you to be afraid even with the two different personalities within them.