We're probably on the brakes until the next Serena-centric episode, or an Ash-centric episode that Serena can have a major role in. Most of the time I've noticed, characters have their personality shining strongest in their opening episodes, and then episodes that focus on them. They really wanted us to know that Serena is interested in Ash because her feelings are probably going to be central to her Character. I mean, in Enter Iris and Axew, we spent a bit of time seeing Iris swing around and be a wild girl, right? Even though in later episodes, she wasn't doing really anything "uncivilized". It's just how they write characters, I suppose.
We'll probably get another Serena Episode before XY25, since she's been out of focus for so long. Where the relationship goes kinda depends on where Serena's character goes. If she develops a goal soon for her to pursue while she's on the cast, it'll probably be the focus of her next episode and she'll need practicing with that. Ash, as seen with May and to a lesser extent, Dawn, has shown himself a pretty good teacher of Pokémon, which would lead to bonding time for the two of them. Ash knows Pokémon more than he knows anything else, so Pokémon could be what finally alerts him to Serena's feelings and helps him reciprocate.
If Serena never develops a goal (or, indeed, her goal is to find a goal), then her stay in XY will be different; she'll instead have to help and motivate Ash while he's on his badge quest. This requires Serena to put herself out there more, but we saw in XY005 and XY006 that she's capable of being there while Ash trains and being a huge support to him. In order to be more helpful, she has to get more Pokémon that could be used as training partners for Pikachu and the others. Again, connecting over Pokémon could be the key that pierces Ash's denseness, and training together would help them grow closer.
Two other things I'd like to bring up. First, on the note of Pikachu and Fennekin mirroring Ash and Serena, why has no one brought up Froakie? I feel like Froakie and Ash have a lot in common. They're both stubborn and brave, putting themselves in danger to help their friends, and not giving up even when at a disadvantage. They're both also prone to outside the box thinking, with Frubbles and unorthodox strategies. But Froakie and Ash aren't 100% 'the same'. Froakie is a better judge of character than Ash (such as trusting Team Rocket's Meowth) and would much rather deal in an eye for an eye than to let bygones be bygones. Maybe Froakie's personality sort of represents a more matured, but lonely Ash. One who cans see through Team Rocket's tricks, but maybe has trouble relating with others. But Froakie also has been seen close to Fennekin quite often, especially in XY011. Froakie has a soft spot for Fennekin, and from them sitting close together in later episodes, seems to be really friendly with it (contrast how Froakie acted to Fletchling in XY006 after the training had ended). Maybe Froakie and Fennekin's relationship is a sort of echo of Ash and Serena's, one that Ash might not be totally conscious about yet.
And on the other note, according to an interview
I read here, Shauna is supposed to be seen as a romantic interest for the male player in the XY Games. This instantly made me think of Serena, especially with how much they're pushing her crush on Ash. A good sign, perhaps, since Ash is basically the "male player" in the series? Hopefully we'll get something from the Parfum Palace Episode.
