Headcanon that Nathan is actually really good at Chemistry. The reason why he always has the "good shit" for parties is because he knows what mixes well, to create the right effects. He also seems to have really bad suicidal tendencies, because his medicine is not supposed to mix. His anti depressants and anti psychotics shouldn't be mixed, much less with alcohol. He's got a bottle of liquor in his room. I'm pretty sure he knows what exactly he's doing.