Tonton Streaming W.I.T.C.H. (2004) S1E17 - The Mogriffs

Phobos sends shapeshifting monsters into Meridian to pose as and discredit the Guardians so Elyon will lose what little trust she has left in her friends. While the real Guardians do battle with the evil twins, Cornelia and Caleb try to persuade Elyon that Phobos only wants her for her power, but she won't listen. Caleb, however, does something to shake Elyon's faith in her new brother: he bows to her. Unnerved by this, Elyon is starting to suspect that Phobos is not telling her everything.