My PI and I don't really get along that well. However, out of all my letter writers he knows me the best (the other letters will be mostly "this guy was in my class blah blah blah"). He's told me before that he doesn't write negative things in letters (because that would kill the student's chances at admission) but may have a lack of positive things to say. To be honest, this worries me a lot and I don't trust him enough to waive my right to see the letter. How would medical schools see a non-waived letter of rec? Should I even ask him for one or just pick another person?
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