I did used to think Fiona's turn to evil made no sense. Then I got a harsh reminder of what happened prior to Ian's run, and realize, no wonder she went to Scourge; Tails' obsession with her was unhealthy and based on a robot version of her, and Sonic used her as a rebound girl while still blatantly pining for Sally. Scourge at least liked her for, well, HER, to give him credit where it's due.
Still, I would hope Tails learned by the time he met Cosmo.
I did used to think Fiona's turn to evil made no sense. Then I got a harsh reminder of what happened
