Rawdon Crawley Jr.
The maternally neglected, paternally indulged son of Becky and Rawdon, Rawdon Jr. eventually ends up being the novel's big winner, at least as far as status and money are concerned. He becomes baronet and inherits the Queen's Crawley estate and the Crawley fortune and doesn't seem too traumatized by his childhood thanks to the care and love of his aunt and adopted mother, Lady Jane.
Rawdon Jr. is the canary in the coal mine of Becky and Rawdon's marriage. Although everything seems to be going just fine on the surface, Rawdon Jr. is suffering from Becky's absolute neglect. Twice, in the presence of Lady Jane, he busts out with some innocent remarks about what his life at home is like. Both times these comments are so alarming that Lady Jane develops a lasting hatred of her sister-in-law (despite initially liking her), which eventually gets Becky exiled from the Crawley family.