A/N: As I'm sure you can guess, this is Yang's side of things. You can't have Sisterly Antics with just one sister, can you? This is loosely based off actual events between me and my own little Ruby Rose, and I regret nothing!

There was only one thing that Yang Xiao Long ever took seriously. It wasn't classes (much to Weiss's dismay), or silence in the library (much to Blake's displeasure), or even combat (much to Ruby's annoyance). She was an ace in class, the library was too quiet, and she had yet to find anyone who could last 3 minutes against her. No, none of those were things that demanded Yang's attention.

However, the welfare and safety of her baby sister WAS something to be taken seriously, and Yang took it seriously. Very seriously.

Now, there wasn't much that Yang considered a threat to her adorable little sister. She did advance two years to be along side her in Beacon, after all. She knew her sister could easily defend herself from physical threats (of course, that doesn't mean she can't rough up some dickheads who might have scratched her in combat class). It was people taking advantage of her naivety and happy-go-lucky attitude that worried her.

And that one guy from that one team that kept staring at her baby sister was practically asking the blonde buxom beauty to make sure he ate from a straw for the rest of his life.

"Yang, you're going to set something on fire if you don't calm down." The smooth tone of her partner brought her out of her thoughts. "Seriously, you've been glaring daggers at that kid for two hours now. Do you even know his name?"

"It's Carlyle."

"Uh, no. It's - "

"It's Mudd, for all I care," Yang interrupted. "He... He's vile!"

Blake gracefully raised an eyebrow. "Vile?"

"Yes, just look at him! Leering so vulgarly at my sweet, innocent baby sister!" She practically hissed in pure and bitter distaste.

"Sweet and innocent? You do remember she beheaded a Nevermore, right?"

"Not the point, Blakey."

Blake stared at Yang as the blonde continued plotting horrible things for the boy in question. She knew her partner was pretty protective of their team leader (she did help track down the guy who shredded Ruby's hood in a fight, after all), but even this was extreme for Yang.

"Yang, your sister is fifteen, she's old enough to like boys."

The look on Yang's face would have been comical if she wasn't a battling, rock 'em sock 'em brawler that had no problem knocking teeth in. "She's too young to like boys! And he's too old for her, anyway!"

"Just two years."

"NOT HELPING, BLAKE!"

The raven-haired girl chuckled at her blonde friend's antics; if she couldn't make it as a Huntress (which was unlikely), she should consider going into comedy. She could see veins practically popping from Yang's forehead and her fists clenching and unclenching in fury. Her reaction to this boy, like her reaction to anything, was over the top and over dramatic.

"Just look at him, Blake. He's not good enough for Rubs, anyway." The older sister gritted her teeth. "I think I ought to teach him a lesson."

"... I have no choice but to go along, do I?"

"Nope!" Yang chirped cheerfully, ideas of torture floating merrily in her mind's eye.

Red and white watched down the hall, side by side.

"Uh, Ruby?"

"Yes, Weiss?"

The heiress grew uncomfortable with her inability to speak around the cheery little reaper, and especially uncomfortable with that... ruffian that seemed to follow her everywhere, and no, she didn't mean her older sister.

She had been noticing for weeks now that Ruby was spending a lot of time with that mousy looking guy from Team VOID, whatever his name was. As the best teammate ever, she felt that she needed to step in and let Ruby know that perhaps she needed to spend less time with him and more time with her, her partner.

Weiss cleared her throat. "Ruby, it has come to my attention that you've been spending too much time with - "

"Oh, Dino!" The redhead, completely oblivious to what the ice princess was trying to say, started waving to the last member of Team VOID, Dino Verde. "Dino, over here!"

The boy lifted his head up and gave a small smile to the younger girl. "Oh, h-hello Ruby..."

"Hey, wanna join me and Weiss in our study session?"

"Uh, but Weiss is..."

"Eh?" The little reaper looked around, finding her frosty partner had disappeared.

"Yang, I don't think that's the best of ideas..."

"Relax, kitten, I got this!"

"You call me 'kitten' one more time, you won't be sleeping for a week."

The blonde winked. "Oh, really? Doesn't that sound... purrrr-fect?"

Just as Blake went to open her mouth, she noticed Weiss watching down the hall toward them and she did not look happy. "Weiss? Are you alright?"

The heiress, not noticing her other two teammates until the raven haired ninja made their presence known, huffed and clenched her jaw. She certainly wasn't going to tell them about how she felt about Ruby spending too much time with that boy... until realization flashed across her eyes.

Yang was Ruby's older sister. Yang took that very seriously.

Oh, this boy was as good as dead.

She sighed dramatically, frowning. "It's just that, Ruby has been spending too much time with that Dino from Team VOID - "

"I told you, Blake!"

" - and I feel that she really needs someone to step in and say something. I feel like..." She paused, considering her next words carefully. She could either calmly point out that they spent too much time together, or she could mercilessly end the kid's existence. She had to trend lightly - Yang Xiao Long's temper was legendary.

"You feel like what, spit it out!" The blonde crossed her arms, impatience settling on her face.

"... I feel like he's just trying to get in her pants, as you say." Of course, as Yang's temper was legendary, Weiss Schnee's spitefulness was the stuff of lore.

Blake looked between the rapier wielder and the gauntlet wearer. From their expressions, she could tell she was in for one hell of a ride. She pinched the bridge of her nose, trying to brace herself for the chaos ahead.

The sun was splashing down upon the world, making the breeze pleasantly warm and beckoning students to rest under the trees. And that's exactly where the newly formed Team WBY's target was. Weiss narrowed her eyes as she glared at the male while Yang's sneer was almost audible, the two in total agreement with the plan.

"Guys," Blake, the only voice of reason in the madness spoke up. "Are you two really sure this is a good idea?"

After a united "Yes!", the ninja knew there was no turning back. At least it was going to be entertaining.

"C'mon, girls, let's get cozy with the boy." The blonde brawler grinned, cracking her knuckles. She made her strides long, each step propelling her towards her target, her nemesis, the boy who dare defile her precious little sister.

The element of surprise was on her side as she caught him off guard and pinned him against the tree by his collar. The absolute terror in his eyes was only egging her on, her grin now turning into a smirk.

"U-Uh..." The poor kid couldn't even form words, frightened orbs darting around to look at the three girls.

"Sooooooo," she drew the word out, her tone calm and casual. "I hear you being hanging around Ruby a lot."

She could feel him swallow before replying. "Y-Yea, your sister is really nice."

"Nice, huh? That the only reason you hang around her?"

"Excuse me?"

Rage flashed across her face. So the kid wanted to play dumb. Yang Xiao Long didn't like it when her prey played dumb. She pumped her fist, feeling her Ember Celica engage, before promptly grabbing the boy's jewels and giving them a squeeze. The boy chomped down on his lip, holding back the scream she knew he was hiding. She had to hand it to him, at least he was being a man about it.

"You stay away from my baby sister, she's too good for you anyway."

"I'm too good for what?"

All four sets of eyes turned to the younger girl, none of them hearing her approach. From the look of her face, it was apparent she had a fairly good idea what was going on. Especially with Yang's grip on the poor male's anatomy.

Yang was the first to speak. "He... asked me to check him for testicular cancer. Yea, that's it."

"You're always doing this, Sis! We're friends, he's not hitting on me, he's not hurting me, he's not doing anything to me! I'm helping him talk to girls so he can ask Ida out!" Silver eyes bore holes into her older sibling's head, a stand off as old as time itself.

"Ida?" Weiss finally spoke up, confused on the situation.

"Yes, you know, Ida from his own team..."

The three girls hummed in understanding as Yang released Dino from her iron grip. She grinned sheepishly as she rubbed at her neck. "Well, y'know, older sister's have to protect..."

"YANG!"

"What!? You're my baby sister!"

"I am so mad at you right now!" The little reaper turned on her heel and stormed away, being followed close behind by her sister.

"Aw, Rubs, come baaack!" Yang sighed. She knew Ruby was going to mad at her for a looooong time. Oh well, she thought, nothing that story time and cookies couldn't fix.