I just finished the first book and went back to rewatch a couple parts of Season 1 to compare to the book. There are multiple angry outbreaks from Claire that don't happen in the book, and in general, she seems to be much more logical and level-headed in the book. For example, in the episode "Rent" Claire gets all pissed off about the feudal system and tries to return a goat to a family who had used it to pay rent, then screams at Dougal for letting children go hungry even though the goat was fair and square payment. And earlier, when Colum tells her he wants her to stay at Leoch for a while as resident physician, in the show she yells back "you mean as your PRISONER!" And when Dougal is collecting payments for the Jacobite cause she gets all judgey about him being a crook before she understands what the money is really for. Book Claire is much more reserved and strategic. I wasn't a fan of season 1 Show Claire from the beginning but now even less so because I know how she is in the book. Like the whole time I am watching the show I am thinking "ugh, SHUT UP, Claire!"