Lee’s comment > Likes and Comments

When he changed Edward and Esme he had a bond with them, so he wanted to save them and spend eternity with them. It wasn't just a random person he wanted to save. And he wasn't completely against them killing humans, it was natural and expected, but he hoped that they would adapt his vegetarian lifestyle.

Also with Rosalie I'm pretty sure he saved her to find a mate for Edward, but she never drank human blood (though she did kill the men that almost killed her). And the last person he changed, Emmett was the mate that Rosalie asked him to changed.

Also I know your comment is almost five years ago, but it didn't have any replies so I just wanted to give you an answer lol