oh man, that's awesome! he has his forensic scientist memories, so he's been very curious about that field. he's a pathologist at massgeneral hospital though, so that's on the other spectrum. maaaaybe they know each other through their work? i know that they can't perform an autopsy if the death was due to some crime, even if they've died there. so barrett could be the one calling the lab to inform them about it and passed on whatever information he had, etc. and maybe the more they did that, the more they hit it off and have become friends?