biggest small change they made in the show was changing ‘jaime lannister sends his regards’ to ‘the lannisters send their regards’ which simultaneously changes nothing (because they don’t do lady stoneheart) and the entire meaning of the line. the lannisters were involved in the red wedding the line is just true now and it’s still cruel but the specific pointed cruelty of the original line was that catelyn died thinking that it was her fault, that she’d been tricked into an oath with the most notorious oathbreaker in the world in hope of saving her daughters and it killed her son. bolton knows she released jaime against robb’s wishes he knows the implication that jaime then arranged for her and robb’s deaths is the single most horrific idea he could give her in her dying moments