Reckless Pacifist: Cassie refuses to kill Aftran because this somehow means killing Karen too, never mind that Karen is a five-year-old girl easily overpowered by any individual Animorph, and they have allies like the free Hork-Bajir and the Chee who could easily contain up to an adult Hork-Bajir Controller for however long it takes to starve the Yeerk. She allows Aftran to infest her instead, putting her fellow Animorphs, their families, the free Hork-Bajir, and the Chee all at risk of Yeerk enslavement or extermination.
This is pretty straightforward, regardless of whether or not Karen's billionaire father was looking for her. Hiding her with the Hork-Bajir or the Chee would prevent Karen from being rediscovered by Yeerks, as the Hork-Bajir valley went unfound until a free Hork-Bajir was re-infested, and the Chee have holographic technology beyond the Yeerks, which means they can have Karen out in public without any Controller realizing it's her.
On top of that, Cassie wasn't thinking about Karen's father or the logistics of having to hide her from the Yeerks when she let Aftran infest her. She was thinking that she couldn't sacrifice Karen to keep Aftran from revealing the Animorphs' identities to Visser Three. Had this been any other Yeerk, the war would have been over then and there, but Cassie would get to keep the moral high ground over her friends.
This is pretty straightforward, regardless of whether or not Karen's billionaire father was looking for her. Hiding her with the Hork-Bajir or the Chee would prevent Karen from being rediscovered by Yeerks, as the Hork-Bajir valley went unfound until a free Hork-Bajir was re-infested, and the Chee have holographic technology beyond the Yeerks, which means they can have Karen out in public without any Controller realizing it's her.
On top of that, Cassie wasn't thinking about Karen's father or the logistics of having to hide her from the Yeerks when she let Aftran infest her. She was thinking that she couldn't sacrifice Karen to keep Aftran from revealing the Animorphs' identities to Visser Three. Had this been any other Yeerk, the war would have been over then and there, but Cassie would get to keep the moral high ground over her friends.