Alex Rider crossover - what's your secret?

Chapter 1

Alex was finally in the safety of a car. He had limped out of a building, clutching the bullet wound on his stomach. The building literally exploded 2 seconds after Alex got out. Luck of a devil again I guess... Alex thought as he limped towards a car parked in the distance. The flames from the building lit up the sky that is dark with heavy clouds. It's gonna rain heavily really soo-. Rain pelleted down and hit him on his head, it soon turned to pouring rain. The lightnings that flashed through the dark sky and the claps of thunder followed almost immediately. Never mind.... Alex reached the car, he broke what remains of the already broken window and open the door before kneeled down carefully and pulled out a paper clip. He then did his magic and the engines roared to life. Alex got in the car and drove off.
He reached the destination of the safe house he was assigned to. Alex parked the car and moved gracefully and quietly on the gravelled path. He then realise that he doesn't have the keys to the safe house. Dammit. Mr Blunt didn't give me the keys, what was he thinking? Alex sighed softly as he pulled out the paperclip and begin trying to unlock the door. That was easy... What kind of safe house is it if you can easy break into it? Alex punched in the code of the security systems and flipped its cover back. He walked to the cabinets in kitchen and searched for candles. He tried turning on the lights just now but it didn't work. It might just be because of the rain. He found what he was searching for and placed it on the island after lighting it. He took one of the lighted candles and moved to the bathroom to get a first aid kit to get his wounds cleaned. When he reached the bathroom's mirror he was shock to see his own face. One eye was swollen shut the other was swollen but not as much. One cheek was bruised and a little swollen. He had a cut above his right eye brow from when a bullet grazed right past and he dodged in time or he would have been dead instead of standing here checking out his face. He has a cut on his neck, right across. Someone tried to slit his throat but didn't slit deep enough and something distracted him which gave Alex the chance to strike back. Alex walked back to the living room and placed the first aid kit on the coffee table. He pulled out the gun from his waist band as he walked into the kitchen and checked his gun. It's a SIG-Sauer P229. He cleaned it and then reloaded the ammunitions and took a few extras. He then tucked it back into his waistband and moved back into the living room. He was about to start cleaning his wounds when he heard the sound of gravel crunching under shoes in the rain. It's only because he was trained to listen to these type of noises was he able to pick it up in the heavy rain.
"Are you sure this is the right place Ziva?"
"I'm sure, Tony! You just asked me that 5 seconds ago!"
Alex walked to the door warily as he pulled out his gun. Ziva spotted someone walking inside the safe house. She gestured to Tony and he showed he understood by pulling out his own gun. Ziva opened the door with her keys and the alarm went off. The sight that greeted them shocked them. They took in a battered teenager that is holding a gun. "NCIS, Federal agents. Put your gun down!" Tony exclaimed. "Turn the alarm off."
Alex regarded them cautiously as he moved swiftly to the alarm and disarmed it before reactivating it's system. "Put your gun down, kid."
"... You put yours down first."
"We're federal agents, you don't order us on what to do, we do." Tony said. "Oh... I'm so scared." Alex replied sarcastically as his aim remain unwavering. "Who are you?" Alex asked. "... I am special agent Anthony DiNozzol." Tony said pulling out his badge. "I'm special agent Ziva David."
"Ziva David..." Alex repeated quietly but they heard him alright as they walked in and shut the door. Alex kept his gun, which surprised the agents who slowly puts theirs away. "Eli David's daughter, am I right?"
"How did you know?"
"We met before."
"When- Oh my... You're that kid that helped me when I was captured you helped me out but you in turn got shot and captured..." Ziva said, shocked and relieved. One-relieved- because her saviour is alive and two-shock-because she never realise that Alex was a teenager till now that she got a better look at him. "My father wanted to thank you." Alex smiled but the winced because of the pain it caused. "Are you alright?" Tony asked worried. If Ziva was saved by this little dude, they can trust him. "Yeah." Alex said as he got to the first aid kit and started cleaning his wound. It seem really painful but Alex didn't even react when the alcohol touched the wounds. "Do you need help?"
"I might need a little help later..."
"Why later?" Tony questioned as he watched Alex wrap the white bandage around his neck. "Alright. I need help now. Ziva you mind?"
"Why Ziva?"
"Because I don't think you know how to remove a bullet." Tony and Ziva paled but they are not as pale as the almost paper white Alex. A battered teenager that is not freaking out now is impossible. But a teenager with a battered body and bullet wound that is so calm is literally like asking a cow to speak a language you know.
Alex pulled out a Steel Eagle 107C Knife (7" Black Plain). It's overall length is 13". He handed it, handle first, to Ziva. Ziva took it as Alex laid down and pulled up his shirt slightly, enough that Ziva can see the wound but not enough that she can see the scars littering his body. He is slim and you can see his 6 pack. "Ziva!!!" Tony exclaimed. "What?!" She paused from whatever she's doing to glare at Tony for shouting at her. "Don't you need to disinfect the knife before you do anything?!"
"Fine. Fine. " Ziva grumbled as she poured some alcohol onto the blade and wiped it clean. "I guess I should cover my eyes so I don't freak people out that I'm staring at someone dig a knife into me to remove a bullet right?" Alex said as he laid an arm over his eyes. "Who are you?" Tony ask trying to distract Alex and also trying to learn something about the kid's identity. "Classified."
"Why?" And new voice said from the door as the sound of door closing was heard.