Betrayed by Rex and rescued from a desperate fight by a pair of mysterious Bretonic vampires.

How ironic to be both betrayed by and rescued by vampires! I loved the welcome touch of humor as the voracious rabbit charged out of the forest!
Let me offer some thoughts that I hope you will find constructive and helpful
Your paragraphs are rather large. In the forums format, this can present a bit of a wall of text. Most of us here try to break our prose into smaller paragraphs so they are easier to read.
Also, I highly recommend you google Dialogue Punctuation and study up on a few of the sites that cover this rather arcane aspect of fiction writing. For now, suffice it to say that a golden rule in fiction is that every time you change speakers, start a new paragraph. Happily, this can also result in much shorter paragraphs.
Regarding lengthening your episodes, actually this current one is probably about perfect, as it is just under 1500 words. I shoot for 800 1800 words; much longer and you begin to lose some of your impact. The reason your episodes appear kind of short is simply that, as I mentioned, your paragraphs are too long.