Mr. B (a.k.a. "The Master" or "The Squire") Timeline and Summary

Mr. B starts out prideful and violent, attacking Pamela and threatening to rape her, like, constantly.
After his last attempt to rape Pamela, which results in her having a near-fatal fit, he starts to reform his attitude and behavior toward her. Thanks to this character development, Pamela's own feelings toward him start to reform.
Meanwhile, because rumors of his behavior have reached the ears of his sister (and others), he ends up in a family feud with Lady Davers.
After some hemming and hawing about their different social stations, he finally decides that he should marry Pamela, and Pamela (having fallen in love with him) agrees. They marry in secret.
Soon after, Lady Davers storms in for a surprise visit, so Mr. B and Pamela are forced to reveal their marriage to her. Mr. B and Lady Davers fight and make up.
Mr. B then reveals to Pamela that he's supporting a love child from a previous relationship, but she thinks she's Mr. B's niece.
At the end of the book, the editor reports that Mr. B and Pamela have a happy life together, and that Mr. B becomes "remarkable for Piety, Virtue, and all the Social Duties of a Man and a Christian" (104.5).