[at time of writing, Volume 3, Episode 9 is the most recent episode released, and it is possible a trailer for Episode 10 may release tomorrow. If it contains anything of importance, this post will be edited.]
Ok, so, WHAT... IS... ZWEI??
(if you're lazy, find TL;DR near the bottom, or actually READ my carefully written post...)
I know, he's a little black and white Corgi dog, I know. He also breaks ALL the rules and is crazy OP! At first you'd think he's just a little comic relief, and maybe that really IS all he is, but there's a difference between Zwei's insanity, and the other forms of comic relief we see in RWBY. Let me explain:
Because it's an anime cartoon, RWBY characters are capable of things that REALLY shouldn't be possible in their world. For example, EVERYONE is capable of super speed. No, really. Did you SEE how fast Neptune, the hydrophobe named after a sea god, could run up a small mountain? Did you notice that when Ruby returns from her meeting with Ozpin, Glynda, and Ironwood about the intruder (Cinder), that Yang, Blake, and Weiss all moved super fast to the door to ask how it went? Plus, Ruby has a secret power to her semblance that lets her turn into a tiny, super-deformed version of herself and levitate in the air... No really, it happened... Or did it?...
See, this is an animation trope done just for the humor and comedy possible with characters that don't have to physically exist. We all knew that, and surely Ruby didn't ACTUALLY shrink down to a tiny form and hover, and Neptune didn't REALLY zip up that mountain as quickly as it seemed, right? Of course! It's just humor. The idea here is that their emotional state resembles this image, and because we CAN, we actually get see it for the sake of the lulz. IF, for some reason, the scene where Ruby shrinks into a cartoony-small form was somehow critical to a story point and was caught on a security camera, seeing that camera footage WOULD NOT show Ruby's comic form because it isn't really happening. In a serious part of the story, silliness like this just shouldn't happen, and we'd fully expect that seeing the same footage in a serious tone would have Ruby being totally realistic and just maybe jumping up and down. So, what does this have to do with Zwei?
Well... Zwei can be crazy in ANY scene he's in... When we first meet him, he literally drops out of a package strongly resembling a Pringles can, and is 100% OK. That should literally KILL a dog, just shoving him in there, let alone requiring air-holes... Oh, and guess what? He was also in there with a MONTH'S SUPPLY OF CANNED DOG FOOD AND A CAN OPENER... Even Weiss and Blake are shocked by his method of arrival. Nobody bats an eye when some other physics-breaking action is performed elsewhere in the show, yet these two characters are SHOCKED by a dog arriving by MAIL, with a large supply of CANNED FOOD... Ok, sure, it's not a serious scene, it's all for the lolz, right? Well, that's pretty wacky, and I guess that's why it's funny, so I let that pass.
BUT, next time Zwei plays a big role is in a BATTLE with an army of angry, unreasonable, half-furries, and their battlemech toys. With literally not a word spoken, SOMEHOW Doctor Oobleck decides to use is flamethrowing baseball bat (which is ALSO a thermos!), to smack Ruby's beloved little pet across a large stretch of train into an advancing mech and knock it off the train... Which works, and to which Zwei is TOTALLY compliant with! He actually jumps up into a summer-salt roll to give Oobleck a good shot. AND RUBY DOESN'T EVEN BAT AN EYE... There is no "Dr. Oobleck! What are you doing with my dog?!" As if this kinda thing happens all the time... And then, of course, Zwei wants to stay behind and "play" with the nice furry-men and Dr Oobleck, so he actually asks Ruby if he can stay behind and she agrees, without a worry for his safety... (9_9)
The next time we see Zwei, is after the train crash and the Grimm invade the city. Right as the hilariously OP team CFVY shows up, a battlemech crawls out of the hole and Zwei jumps off, stupid tongue swinging, and headbutts the nearest Grimm and supposedly proceeds to kick more butt... Waitaminute... Why did the mech climb out of the hole? Nobody got out of it... Dr. Oobleck likely has no need to drive, since he's always hyped up on espresso anyways... Oh my... WAS ZWEI DRIVING IT?!?! No, really, WHO WAS DRIVING THE MECH?!?! Why would a WHITE FANG PILOT be so CORDIAL as to drive a LITTLE HYPER-DESTRUCTIVE CORGI up out of the hole and into his next battle scene?? We never see anyone get out of it, and Oobleck and his buddy Peter Port meet up shortly after to join the fray. Oobleck PROBABLY wasn't driving it... That only leaves... ZWEI!!!
You see what I mean? Sure it's funny, and I'm not complaining. I'm not standing here saying "Oh please! You just ruined the immersion for me! Thanx RT!". No, not at all. I'm laughing my behind off. But still, this kinda thing... SHOULDN'T be happening. This isn't just humorous exaggeration of emotion, capable of existing because it's a cartoon. This HAS to be happening somehow... So...?
The last we've seen of Zwei at this point, is him randomly showing up in Yang's room, when he has literally not made ANY other appearance the whole season, except for briefly standing next to Ruby's father in the beginning of Episode 1. That's all. And now he's back? How did he get into Yang's room? Did Tai-Yang mail him back again?
[EDIT: He was actually sleeping on one of their beds in Episode 4, so, apparently, he's been with them all season... Go figure. I can't believe I didn't notice him!]
So.... WHAT IS ZWEI??? Is he the most elite guard dog known to man? Has he received special training in manifesting his aura? Is he the "One Punch Man" of dogs? (The "One Punch Puppy", if you will?) There was an interview with Ruby and Yang themselves, where fans got to ask questions. Look here for the link, but to sum up, they both simply acknowledge Zwei as the most powerful force known to man, and that's about it... Riiiight.
So, you know I've got a theory, right? (-_^) While I'd LOVE to hear everyone's input, I also gotta give my opinion on what Zwei is...
So, my best guess, is that Zwei is actually, an insane, BUT benevolent, deity... yeah. And he decided, it would be REALLY fun, to be a dog!.. Yeah. And he thought it was SO MUCH fun, he kinda decided to just, STAY that way, forever!.... yeah. And got adopted by Tai-Yang, who is such a dunce that he thinks this is normal dog behavior... yeah. And Ruby and Yang don't know better because they grew up with him, and why they are completely unfazed when their beloved pet drops out of what should have been a death trap: the Pringles can.
Kinda like THIS scrappy little fellow... (read the descriptions!)
I can't wait for Ruby to try to shove someone else's dog into a Pringles can, and wonder what went wrong...