Fenna was first seen whimpering after being abandoned, but she was chased by Team Rocket, but Gabe rescued her and she chose Gabe as her trainer. In one episode, Team Rocket attempted to steal all of Gabe's Pokemon including Fenna, but Gabe protected her. As revealed in Fenna Evolves, Fenna doesn't want to evolve and when she started to evolve, she stopped the evolution by using bind.
Fenna after being abandoned by her trainer was shy and often whimpered a lot. But after Gabe rescued her, she chose Gabe as her trainer. She still is shy due to being abandoned, but has warmed up to people a bit.