What's a wonton person?

Wonton is a type of Chinese dumpling, so you probably mean wanton. This adjective has several meanings: undisciplined or unmanageable (Do you have a wanton appetite for fried wontons?); sexually loose; senseless or unprovoked; deliberately malicious; and arrogantly ignoring justice or decency.

In Charles Dickens's David Copperfield, Littimer (Steerforth's personal manservant) is a formal, haughty man who has an air of respectability — yet he aids Steerforth in his seduction of Em'ly. Littimer is later captured and sent to prison:

[Littimer] surrounded himself with an atmosphere of respectability, and walked secure in it. . . . To have imposed any derogatory work upon him, would have been to inflict a wanton insult on the feelings of a most respectable man.