I love Arima, but I suspect if Tsuneyoshi had treated Furuta as a pariah after Rize (which is strongly implied), Arima would have gone along with it, at least on the surface, so as not to risk his plot with Eto.
No doubt he saw potential in Fruit-chan, but I also suspect he noticed Furuta’s crueler instincts – or at the very least that he was hiding something – and may have avoided him as a result. Furuta is not exactly a trustworthy aid.
Else Eto would have skinned Arima.
His favorite? Hmm. I wish it had been Hairu; she deserved it. My guess is he tried not to develop such close relationships so he wasn’t devastated by their deaths. 😦
Mercy and Magic 