The answer to this question depends on what you mean by wanton. A dictionary will give you something like the following definition: a wanton character is one who is merciless, lewd, malicious, undisciplined and spoiled. Given these adjectives, and thinking about this excellent bildungsroman from Dickens, the major character that could be described as wanton would be James Steerforth. In the novel, he is an attractive, charming individual who nevertheless shows himself to be completely unprincipled and incredibly selfish in the way that he uses others, especially David Copperfield in his innocence and naivety. Throughout the novel, Steerforth only uses David for his own ends: to gain prestige and status through the connections that David has and then to cruelly betray him. The way that he preys on the innocence of the title character is obvious to us as onlookers, but is used to emphasise the innocence of the narrator.