Comment by Anya knows you read this kind of stuff on Geann.

Ideun tested negative for a drug test tho, so I think he wasn't really exposed to any drug. As Ideun said, he used s** to get tired so he can fall asleep, cause y'know, insomnia. Jintaek would never have threatened Ideun to do something such as forcing him to do something that resulted to his current behavior. 1: There's no merit for Jintaek, 2: I think I saw in one of the chapters, vaguely, something like "Oh, so you came here to do that." I don't know what 'that' is yet, but we'll find out eventually. But I agree, something's def going on with Ideun that's related to Jintaek's death. 

This is only my opinion tho, pls don't come at me