Bran...well, Simon would likely be torn on how he's supposed to react to the apostate. On the one hand, his templar training is going "PWN HER, PWN HER, DANGER WILL ROBINSON, DANGER". But the other side of him not taken over by the Chantry is going "Well, she's helping fight the Darkspawn; she can't be that bad". Killing off apostates simply for not bowing to the Chantry is one of those things that he questions most of all. But if she decided to try and turn evil (or be taken over by a demon), then he'll have no qualms about acting out his Templar duties.