I think that he had something else going on, but I don't think it's either of what Sue assumed.
I agree with your thinking that he was just trying to be advanced, because a lot of the words he did try to use he didn't use correctly.
If I had to guess, he probably had some more advanced form of depression.
He didn't really have any of the dead giveaway symptoms of BPD, like mood swings or unable to control anger. If anything, I'd say Eric matches that more.
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