Mr. Dolphus Raymond is a white man with a black mistress with whom he has children of mixed race. This is very taboo in Maycomb, a town with a strict, rigid code of separation between the black and white communities. That code is so rigid that it is rumored, as recounted by Scout, that Mr. Raymond sent two of his children to the north where they would be more readily accepted in society.
Mr. Raymond always has a bottle in a brown bag and people assume that it is filled with whiskey. Thus, they assume he is a drunk. However, when Scout takes Dill out of the courtroom to calm him down, Mr. Raymond gives Dill a drink and he discovers it is Coca-Cola, not whiskey. Mr. Raymond explains that he pretends to be drunk because, for people who don't approve of his lifestyle, this gives them a reason to justify his behavior:
“I try to give ‘em a reason, you see. It helps folks if they can latch onto a reason. When I come to town, which is seldom, if I weave a little and drink out of this sack, folks can say Dolphus Raymond’s in the clutches of whiskey—that’s why he won’t change his ways. He can’t help himself, that’s why he lives the way he does.”
Knowing the racist tendencies in Maycomb, Mr. Raymond acknowledges that some people won't understand how a white man can be with a black woman. Mr. Raymond entrusts Scout and Dill with the secret that he fakes being drunk because they are children, too young to have been brainwashed by the racist social codes of the adult world. Mr. Raymond wants the children to keep the secret so he can sustain his reputation of being a drunk, thereby giving judgmental people a reason as to why he would want to have children and be with someone of another race.