You look like Zero from borderlands, your semblance is his kill skill (Decepti0n), you use a sniper and an SMG as well as his sword. On to the story!!

RWBY POV
"So... Ozpin sent us to find an assassin who's name we don't know, bring him to Beacon despite not knowing what he can do, and find out why he killed those people all without attacking him?" Weiss said.
"Yep, sounds pretty boring to me." Yang said, putting her hands behind her head.
"Just so long as we follow our orders, we should be fine." Blake said.
"Do you think he's really all that bad?" Ruby said, looking at her four teammates.
This got looks from everyone. Next thing they knew was they heard gunshots and shouting. A man wearing a bladed biker helmet was thrown out a window and landed on the ground with a sickening crack.
"I'll get you for this... vault... hunter..." The man said before falling unconscious.
  More gunshots, screaming, and bone breaking could be heard from the house. So, the four girls rushed in and drew their weapons.
They saw a man wearing a thin suit with body armor and a helmet that covered his face standing near the edge of the room with a light blue strait edge katana pointed at another man's throat.
"W-w-what do you want to know!? I-I'll tell you everything!!" The man on the floor said.
"Who has sent you here? / Why do you attack me still? / Don't you know of me?" The man in the helmet said, with a slight echo and muffle to his voice.
"W-we were sent to get you by someone in a dark green cloak! He paid in cash, that's all I know! I swear!"
"You lack the knowledge. / You also lack the skill set. / You can not get me." And with that, he cut the man's head clean off.
"W-w-why did you do that!?" All of team RWBY yelled, almost in unison. The man didn't flinch. He only turned around to face them.
"They tried to kill me. / Is it a sin to fight back? / They were just bandits." The man said.
"YOU JUST KILLED HIM WHILE HE BEGGED FOR MERCY! HOW IS THAT SELF DEFENCE!" Yang yelled.
"They would do the same. / They would rather just kill me. / It's my life or theirs." He said.
Yang then rushed at him, but passed right through him. He then started swinging his sword around.
"Um... why are you doing that?"
They then saw Weiss fall down and the man stand over her, staring down at her.
"H-how!?" She yelled.
Next was Yang. She fell down with her aura depleted, and the man standing behind her instead of over Weiss. Then Blake's aura shattered and her weapon was stabbed into a wall.
The man then appeared in front of all of them.
"How did you do that!?" Weiss yelled, clearly angered.
"Semblance." Was all the man said.
Just then, Ozpin walked in.
"You are the assassin called Zero, yes?" Ozpin asked. The man nodded. "Good. I would like to offer you a position as a student at Beacon Academy."
"On one condition. / I am allowed my helmet / and my precious sword."
"You may have both. But tell me, is Zero your real name?" To this the man shook his head. "Then can you tell us your real name?" The man shook his head again.
"Also, why do you speak in haiku?" Blake asked. The man shrugged.
The next day was... eventful. The assassin (you) was introduced to the class, but never talked to anyone. It Wal kill he wasn't even there. When class ended he vanished. Literally, he just disappeared and appeared in his next class. Well, until lunch. Nobody saw him eat, but his food just... vanished.
When team CRDL was bullying on any faunus unlucky enough to get in their way, he walked over to them.
"Hey look guys, it's a freak in a mask coming over! Now we don't have to mess with a freak with ears!" Cardin yelled right next to the poor wolf faunus's ears, making him flinch.
"You really should stop. / If not I will make you stop. / You would not like that." You said, staring Cardin in the eye. Cardin, being the meat head he is, tried to punch you, only for you or disappear when his fist made contact with your double.
You appeared behind him and flipped him over, making everyone stare at you wide eyed.
"Do you understand? / This could have been avoided. / Don't do it again." And with that, you walked off.

The next few weeks were like that, with you beating up team CRDL whenever they did something wrong.

Your POV
You typed away at your computer, preparing a message to your father over the echonet.
'Dear Father,
    I am now a student at Beacon Academy. I have come to use your former name of Zero, and I am using what you taught me well. I am keeping a group of bullies in line, making sure they don't hurt anyone. Tell mother I said hello and that I enjoy it here in Vale, and also that she needs to keep oiling her arm.
Sincerely, your son, (Y/N).'
With that you closed your laptop. You decided tonight was as good a n8gbt as any to get some fresh air. Unknown to you, Ruby decided the same thing.
You walked into the nearby forest and looked at the guns your friend (and bartender) Moxxi gave you. An SMG that shot acid, a shotgun that shot fire, an assault rifle that shot acid, and a pistol that shot electricity. Your sniper that your father gave you was strapped to your back. Lucky for you your echo device (given to you by your best friend growing up, Claptrap) could turn your guns into a digital format and carry them for you. Makes holding on to them a lot easier, you know? You then saw Ruby, making your heart beat a little faster. Oh no... you were developing feelings for her.

Ruby's POV
I decided to take a walk in the forest to clear my head. Ever since we found that new transfer I've had these strange feelings. His voice sends shivers down my spine, seeing him made my heart beat faster and my face get warmer, but I don't want to like him because of how he nearly killed the rest of my team. It didn't help when my scroll started ringing from an unknown caller. Against my better judgment, I answered.
"Hello?"
"Look behind you."
I turned around and saw... nothing. But I felt someone place their hand on my shoulder. I looked up to see... Zero.
"H-hey." He said.
"H-hi... Zero..." I squeaked back. 
 I wasn't expecting what he did next. He actually took off his helmet. Even when he was in class, he never took it off. Honestly, he didn't look that bad. Those soft, plump, kissable lips... 'Ew, no Ruby! Stop thinking like that!' I mentally slapped myself.

Your POV
I debated my next choice. If I told her how I felt, I risked ruining my friendship with her. I doubt she returns the feelings... but I still had to take the first step.
I leaned in and kissed her. What surprised me was she didn't jump away or smack me. Must've scared her.
I leaned away.
"S-sorry, I just..." I mentally face palmed. 'Idiot! Now you don't have any chance with her!'
"A-actually... I wouldn't mind if you... did that... again?" She said. My eyes widened. Does she share the feelings? Acting on pure instinct I kissed her again, wrapping my arms around her waist. She kissed back, wrapping her arms around my neck. The kiss was long and passionate, just us two, lit up by the light of the moon. I licked her lips, and she opened her mouth slightly. Our tongues danced as if we had done this before. We broke the kiss due to needing air, leaving a thin trail of saliva between our lips.
We both had a shade of blush on our faces that made her cloak look white.
"We should probably head back to beacon. Want to continue this in the morning?"
I nodded, kissing her again. This has to be the best moment in my entire life. I have the girl of my dreams admitting that she would be the love of my life.

[NEXT MORNING]

Still your POV
I opened my eyes, getting my gear on. Today was a day off, so I decided to wear my dad's old "Spider Bite" suit.

It matches Ruby's clothes, so why not? We are dating now. I stepped out of the room, only to see Ruby standing in front of my door. I smiled, causing a (F/C) :) to appear over my visor. She smiled and hugged me, and I instantly hugged back.
"You wanna go on a date today?" She asked, clearly excited. You smiled at her enthusiasm.
"Now that sounds like fun. / Where is it you'd like to go? / I will pay for it." You looked at her, joy in your heart.
"There's this great bakery I know! They make the best cookies! I heard they also started making cheesecake!"
You smiled, knowing you two were going to have fun together. You tilted your head to the side, trying to think of the name.
"Oh, the bakery is called Sprinkles Goods, it's a small business but everything tastes like God made it. You'd like it!" She smiled.
You couldn't help but chuckle at her enthusiasm and hug her a little tighter. She was so cute when she was excited.

You walked up to the bakery, seeing a buff man throw two teenage looking boys out.
"You can't have any cheesecake if you can't pay for it!" Said the buff man.
"But I don't have any money!" Said the boy wearing a black and red particle mask with bandages covering his left eye.
"Is this how you treat all your customers!?" Said a boy with olive dark skin and emerald green eyes.
"*sigh* And they serve Neopolitan cheesecake..." Said the one with the mask.
"Anyways, I'm Galco, you?" Said the tan one
"I'm Sangue, pleasure to meet you." The masked one said, shaking the others hand.
Ruby and I walked past them, not wanting that little moment to ruin our date.
"They're both writers, I'm kinda surprised they never met each other before. They both just love cheesecake, so I think they'll get along well."
"I believe that's good, / People making friends is nice. / Like how I met you."
She blushed and smiled, kissing the cheek area of your visor. A (F/C) 0//0 appeared over your visor, showing that you were blushing.
Soon enough you two ordered, sitting at your table, enjoying some baked goods (which you paid for, being a gentleman and paying for your little lady).

Yang POV
I was searching Vale for Ruby, because she left a little not saying "I'm going out, be back tonight, don't wait up. -Ruby"
She never does this. I decided to check her favorite bakery, Sprinkles Goods. What I saw made me smile. I saw her and Zero sitting at a table, sharing sweets. It was kinda weird watching him eat. His visor opened but it was pitch black, making it hard to tell if he were eating it or what.
"Thanks for treating me, Zero. It's nice to have you as a boyfriend." Ruby said, making me smile a little more. My baby sister has a strong man to look after her. I then saw a (F/C) 0//0 appear over his visor. Daww, he's blushing!
"Ruby, my dearest, / My real name is not Zero, / I should tell you it." He said. Heh, he always speaks Haiku. What shocked me was when he took off his helmet. Damn, if he wasn't Ruby's boyfriend I'd take him for myself. "My real name is (Y/N)." He smiled, and kissed Ruby on the cheek. She blushed, and kissed him on the lips.
I think I should get a picture....

Ruby POV
I heard the sound of a camera and saw the flash of one. When I looked towards the source, I saw my older sister Yang holding her scroll with a smirk on her face.
"You know sis, you and Zero make a cute couple. Or should I say... you and (Y/N)?"
(Y/N) smiled, kissing me again. "Looks like the secret's out. I love you, Ruby Rose."
I smiled, knowing I had the best man on Earth for me. This was going to be a wonderful life.

So... you guys (and maybe gals?) like it? This was actually kinda fun to write. Any ways, see ya in the next chapter! I've already got some of it written out now. Ciao!