FictionOnlyReader
I think, the boyfriend is a 'plant' by either, Dumbledore or abates, … or some other enemy… who knows how their parents died… Well programmed 'plant' or 'identity theft' so that, even mind reading, background checks, can barely detect malice or intention … Only trigger words brings back memory or certain action to make link to their family …
I know Quinn have rules to his mind reading abilities so he won't get too close to the dark side and stopped trusting people etc, but I think every rule has an exception, and in this situation, involving his sister's well-being, it is definitely one of them.. He should have read her boyfriend's mind, no questions asked, and kept it to himself if everything was all right....