I wonder when the fandom will remember that Vee's going to get ALOT bigger and scarier as she grows up.
This isn’t exclusive to that one basilisk either, all the others she was with developed the same traits. (granted not as pronounced, probably cause they’re still young)
(You may be wondering, why they would look so different, but I a theory for it)
Tyrannosaurus Rex wasn’t just the single most massive and powerful predator that lived on land, it was also the only large predator on its continent during its entire reign. This was due to a rare form of Ontogenetic Growth,(which is the physiological changes in an animals development). Unlike other animals who are simply smaller and/or less formed versions of their parents, ala most reptiles, mammals, and even birds. The chicks of Tyrannosaurus were much daintier and more gracefully built than their parents; with smaller skulls/teeth and longer legs proportional to their body mass. This allows them to run much faster and catch smaller and more nimble prey than the adults, thus avoiding direct competition for food with them in youth. Only ages 14-18yrs old do their adult traits rapidly develop. Their bodies/limbs beefing up immensely, their teeth/skulls becoming more robust to take on the large prey they subsisted on as well as compete for territories against rivals. This combined with the protection of their parents allowed them to push out all other intermediate predators,(save Dakotaraptor), and monopolize the entire predator niche of Late Cretaceous North America.
As you can probably tell by close inspection Vee’s differences in appearance to the Greater Basilisk line up very well with the T-Rex. Her jaws/fangs are considerably smaller with her neck also being shorter/skinnier. In contrast, the fully developed adult basilisk could easily devour both an abomination and Willow’s buff plant monster whole. But it seems that while basilisks draw a lot their powers from magic, it doesn’t play a directly vital part of their immediate survival as Vee appeared no worse for wear with her magic shortage. And seeing as she also didn’t hesitate to attempt snapping up Luz as a treat it’s safe assume adult basilisks are carnivores,(or at least predatory omnivores like coyotes/hornbills/bears). Vee and perhaps even her slightly more developed peers on the other hand would likely fail spectacularly trying to replicate this,(not that would if they could either). So its safe to assume that whatever they would be going after, it would generally be both smaller and more manageable such as the demon rats/birds, magical objects, fruits/plant matter, and even cooked foods. This allows both youngsters and adults to occupy a territory without completely depleting it in a short period of time. This may initially seem hard to believe, but note the giant basilisk wasn’t exactly normal, as Vee explained her peer’s ravenous behavior stems from the major psychological damage their constant experimentation they were subjected to by Belos. In reality, Basilisks would’ve drained and consumed only one or a couple creatures in a single sitting to prevent prey stocks from running out.
At the end of the day however, this is just fun speculative biology/evolution, unless confirmed by the creators take everything I say as only theory not canonical fact. This also isn’t here to say that Vee or any of kind are naturally “evil,” it’s clear cruelty/violence isn’t inherent to them no more than any other witch or demon in the isles. Thank you for your time and remember to hug and praise our sweet baby eel.