How we cite our quotes:
MRS. PEARCE [patiently] I think you'd better let me speak to the girl properly in private. I don't know that I can take charge of her or consent to the arrangement at all. Of course I know you don't mean her any harm; but when you get what you call interested in people's accents, you never think or care what may happen to them or you. Come with me, Eliza. (2.152)
On the other hand, Mrs. Pearce suggests that, under certain circumstances, Higgins's manipulation is inadvertent, and that he is even capable of losing control, of manipulating himself.
HIGGINS. [After listening to Doolittle] Pickering: if we listen to this man another minute, we shall have no convictions left. (2.284)
Higgins, himself an expert in language, acknowledges the (sometimes dangerous) power of language and rhetoric.
MRS. HIGGINS. You silly boy, of course she's not presentable. She's a triumph of your art and of her dressmaker's; but if you suppose for a moment that she doesn't give herself away in every sentence she utters, you must be perfectly cracked about her. (3.203)
Mrs. Higgins, like Mrs. Pearce, seems to agree that Higgins can get carried where his "art" is concerned. He seems unable to acknowledge how artificial Eliza's behavior is.