(i) This has been said twice in the play. On the first occasion, it is spoken by the intruder while revealing his plan to **** Gerrard. Secondly, it is spoken by Gerrard before he reveals his fictitious identity to the intruder.
(ii) The intruder' surprise is that he plans to Gerrard and take on his identity. So that he can be free to roam about. Whereas, Gerrard' surprise is his fictitious identity, his way of stopping the intruder from ***** him.
