Wow. That was great. A couple of things I noticed in particular:

1. Shauna getting Stephan's name wrong was hilarious. Now he has to remind a whole new group of people how it's pronounced.

2. If every appearance of Caitlin is going to be accompanied by the shattering of a glass, I'm going to start wondering if she's actually the one shattering them with psychic powers.

3. Regarding the Voltlin scene... just be cautious, and make sure that the relationship isn't just physical activity. If a relationship manifests primarily in physical activity, it ceases to be about the people themselves and becomes solely about their bodies. The two people then cease to relate to each other and begin using each other. It might be good if you backed off just a little. That said, there are plenty of non-physical ways for Volan and Caitlin to relate to each other (gift giving is one, just as an example). Just a friendly reminder.

The Kalos Gang was adorable~ Volan definitely cannot betray this one.
Regarding the sin you had wrote, I must remind you of the risk losing an old reader as not all can adapt toward such development. It as if Yokai Watch suddenly decide to go mature by adding some romance between Keita and Fumi while threwing a genocidal Yokai into the story (Has that happen? If it did, I am sure you understand what I'm saying). Some may like it, some may not. It will thus cost an amount of followers. I am not saying you should stop, I am just stating the risk. It is your story. If you do not care about the fanbases, go on. Unleash your imagination and confirm our theory that Pteromyzon is indeed an 'accident'. Best wishes~

A good Christmas special.
Happy Holidays!