Flareon is what you would get if Scarlet were younger and had the mindset of an "I'm-just-coming-out-of-my-teens" young adult, and if Rosie didn't have a moral compass. Attractive and fully aware of it, Flareon is parts manipulative, hedonistic, and at times, just a troll. The only thing Flareon cares about is having fun and doing things that make her feel good or sexy, which makes her quick to disregard others above herself. While these things aren't bad in and of themselves, it does make her rather unfeeling towards everyone else unless there's something in it for her. That said, the one person she respects, even if a little bit, is Kirby. She has gone on record and told Kirby that she actually feels like garbage when she goes too far and Kirby is truly disappointed with her. In truth, the Johto adventure meant a lot to her, and as a battling Pokemon, she's actually very loyal to Kirby and even protective of him, so she isn't just about self-gratification. Like Nidorina to Kine, though, Flareon still likes to mess with Kirby and play flirt with him just to get him flustered.
Flareon is usually game to do anything if it seems controversial just for the thrill of it, as well as to enjoy how much of a rise it'll get out of people. When she found out that Umbreon was going out getting involved with illegal activities such as theft and defacing property, she wanted in as well, just for the fun of it. This was all well and good (relatively speaking, of course) until Umbreon succumbed to his Evil typing (what Dark type is referred to in Japan) and wanted to start offering blood sacrifices of the innocent for insane reasons. At this time, Flareon tried to stop him, but was unsuccessful. This, along with the threat of getting Flareon spayed—which led to a back and forth power struggle between Kirby and Flareon that eventually escalated to the aforementioned honest disappointment of Flareon's behavior—resulted in Flareon's decision to make an effort to clean up her image and try to allay her hedonistic thrill seeking impulses. It's not always successful, but she has enough love for Kirby to make some kind of effort for him.