Feral forms are the quadrupedal forms for werewolves in my headcanon. They're very noticeably different from that of normal wolves. The feral form is noticeably more stocky--for the standard werewolf, they're much stockier than Lupin is presented here, I actually made her thicker in her limbs and body style than I had intended--and more defined in muscle, as well as thicker in the limbs, somewhat similar in respect to big cats but not quite. The feral form also has opposable thumbs, just like their beast form: useful for taking down prey and gripping it more effectively, as well as climbing or holding.

Just like in their beast form, the feral form is very powerful and despite the stocky appearance, their endurance for running for extended periods of time as well as over long distances is just as good, if not better, in this form. However, most werewolves who are built more for power than for speed tire quicker. Lupin was built for speed and endurance, so she can last longer because of her slightly longer limbs.

Lupin also looks poofier than she really is because of that thick mane of fur at the back of her neck. It's very useful in fending off sneak attacks aimed for her neck, similar to a lion's mane. Unfortunately, it only covers have of her neck and doesn't protect the front.