>>51026439Generally speaking, her development was from being indecisive to being decisive. She couldn't stick with anything she set out to do. Her pre-series character was that she'd always say "I wanna do X" or "I wanna become Y when I grow up", but the second things started to get difficult, she'd immediately give up, drop that interest, and move on to the next interest she'd inevitably drop, too. This is why her mom would continue to push her to continue the "family business" because she assumed, at the end of the day, it'd be all Serena would be able to do with proficiency since it'd be the only constant in her life in between all the passing interests. This is clearly shown by how, when Serena then decides to become a performer, her mom's first response is "Nah, you're just going to quit when it gets hard just like every other hobby you've 'decided' to pursue. Now, c'mon, you're coming home with me to resume Rhyhorn Racing practice." It was under the influence of others she'd met on her travels, principally Ash and Aria, pushing the "never give up" attitude, and all the COTDs she met who became confident in their goals, that she did, too.
Cut to Journeys and you have Serena essentially acting to Chloe like how Aria acted to her, all while quoting Ash like a broken record, now being the very decisive one encouraging others who are now the indecisive ones she used to be.