Going from being annoyed by Psyduck to actually having sympathy for it most of the time? Pretty much any time Togepi was in danger from anything? Helping Ash after he lost the Kanto league, calling him "her burden" and generally being mentor-like at most times? Helping Brock win over that chick that wanted to marry him? Helping both of those two when they were sick? Trying to cook at some point in Johto, even though she was bad at it? Helping Max be more nice to his sister? All of these are just from memory. She didn't just start acting motherly, she became a more tolerable person to everyone around her and it becomes very evident as the series goes on, especially towards the end and after it. I don't know how you can parse through Serena's one-dimensional and currently undeveloped character and act as if there's been any difference in how she's been portrayed during the course of the first forty episodes, then say that Misty was warped into anything.
In fact, now compare her to Serena. What's her most defining characteristic? Her crush on Ash that came about from that single time they met earlier in their lives that had never been mentioned before in the show. Is that going to develop from Serena's end? Probably not; how much more can you even do with it since they established in the first three episodes that she almost certainly feels this way? The writers will just keep dropping the same type of hints as they have been since the beginning to satisfy the insatiable shippers that care far too much about that sort of thing on this show. Is that going to develop from Ash's end? lolno; Ash isn't a human, but an advanced automaton Clemont devised cloaked in the pelt from an actual, emotion-capable person that he slayed at some point before his journey began. Wow, what an interesting friendship! It makes me wonder why the writers even decided to put so much of a focus on it when it's such a dead end in terms of character development and such one-sided interactions between the two. I know anybody who cares about shit like developed characters probably isn't the target demo of the show, but this is bad even in Pokemon terms.
The entire second-to-last episode of the original series revolved around the fact that it wasn't about the bike; she's still the only main character who left that didn't actually want to. And every other companion has either copied the concept in some form or been straight-up retconned into the series. Again, if anything, she had the strongest reason for joining and staying the group: because she wanted to both when she joined, to when she had to leave.
and also:
fuck that I would break his goddamn legs and forced him to carry me around everywhere after they healed if he didn't pay me back for that shit
