Going on his own, Ritsuka tries to get a sample of Eren's blood with the intention of Chaldea analizing it, but things quickly take a turn for the worse when someone unexpected appears.

The word had alredy been given by Dot Pix, Eren's Titan would be used to seal the hole in Wall Rose made by the Colossus Titan during his attack, thus preventing other Titans from breaching the perimeter and threatening humans.

Good plan, and best for Ritsuka it was that Eren would have the night to rest, thus he could get close to him and grab the blood sample he needed, all looked great for the Master of Chaldea.

So he decided to wait the day ot talking to Reiner and Berthold, both of which showed interest in becoming closer to Ritsuka, so even while knowing the two wanted something out of him, he decided to play along. Even with that, he would be lying if he said he didn't enjoyed his talks with the two soldiers and a bond started to slowly form between them.

However, it wasn't time to think about that, for the night had alredy arrived and Ritsuka set his plan into motion.

Applying what his Assassin Servants taught him, Ritsuka entered the place where Eren was sleeping as quietly as possible, careful not to make a single sound. Armed with the syringe in hand, he planned to take his blood and get out as fast as possible, but then...

The door immediatly opened, causing Ritsuka to escape to the darkess of the room while 2 figures entered, the voices making clear who they were, Armin and Mikasa.

"I hope Eren will be fine, he has to fill the hole tomorrow" - Armin said while carrying something.

"He's going to be, you know him. If he's determined to do something, he'll do it no matter what" - Mikasa replied while she got close to Eren's face - "I hope he's sleeping well" -

As they both were going to leave, Mikasa stood in the open door for about a second before talking.

"Hey Ritsuka, I want to talk to you about something, please come outside" -

While he had the skills, they still weren't perfect.

Hiding the syringe, he came out alongside the other two before Mikasa tried to punch him in the face, but he quickly reacted and blocked the hit.

"What are you doing exactly in there?" - she asked while keeping herself ready to fight if needed.

"I came to check up on Eren, but I panicked when I heard someone enter and I hid without thinking twice" - Ritsuka answered.

"That sounds suspicious and I think you alredy know that" -

"I'm telling the truth here Mikasa, I promise you. I won't hurt Eren" -

"Promises can be broken, I need actions Ritsuka" -

"What exactly can I do at this point? It's the middle of the night" -

"Follow me, I'll show you" -

Mikasa and Armin, who stayed silent due to fear of Mikasa erupting against Fujimaru led him to a somewhat abandoned part of the District in which they were on.

"The action I want is that tomorrow you'll help us defend Eren while he seals the hole. You seem to have a lot of skills, so I hope you'll at least find out how to use the ODM" - Mikasa explained why they were there.

"Wait, you can't be serious, according to Reiner you've been training for about a year with this and you want me to learn to master it in 1 night?" - Ritsuka said while nervous about what was going to happen.

"I don't need you to master it, I need you to learn to use it and not get yourself killed" -

"Mikasa, are you sure this is a good idea?" - Armin asked, also nervous about the attitude of her friend.

"Yes" - she answered simply.

Mikasa was, no doubt, incredibly rough, but Ritsuka knew that on a deep level she was right, at this point he couldn't stay just giving orders to his Servants, especially not with the sometimes unpredictable movement of the Titans. Whether he liked it or not, this was a necesity.

And as such, in that small abandoned, Ritsuka's training with the ODM began, and it was a pretty quick one. Mikasa's objective was to teach Ritsuka how to use it and help them during the battle tomorrow, in which she... Kinda succeded?

While he comitted several mistakes falling and hitting himself pretty hard either in the ground or in the roof of some house, he managed to get the hang of it fairly quick and, while slower than the rest, could alredy propel around the houses.

In reality though, this was all due to Da Vinci's help from Chaldea, as she was pretty much commanding everything Ritsuka did in the ODM because of the necesity of the situations, and while she knew he would get hell from the Servants once they found out about what he did, they would at least understand.

With the help from the Homo Universale, Ritsuka could now propel trough the building easier, even if his level was lower than even those from the Cadets. Because of this, he would need to stay close to the Servants at all points because both Fujimaru and Da Vinci knew that he was probably going to make mistakes during the battle, and the Servants were perfect to save him.

The training went on from 10 pm to nearly 4 am, when a familiar voice stopped both of them.

"What are you doing?" - Annie arrived to the scene, looking at both of them with confusion.

"He's going to help us tomorrow, so I'm teaching him the ropes" - Mikasa answered.

"A few hours are not enough to learn to use an ODM and you know it" -

"Ahem" - Ritsuka got the attention of both as he started to swing from building to building, all while Da Vinci directed all of his moves from Chaldea. They both made quite the team.

"He's good, but that speed is going to get him killed" - Annie replied - "He's better off not being in the formation" -

"Don't worry about me Annie, focus on staying alive yourself" -

"What?" -

"I've been in my fair share of dangeous situations, this is just another one of those" - Ritsuka replied as he landed in front of the 2 girls - "I'm going to help you out there, no matter what" -

And with the, he returned to the cmap to sleep even as much as 1 hour.

"Alright, you managed to get at least decent with the ODM, but we missed on his blood" - Da Vinci said.

"Yeah, I'll get it as soon as I can, I promise" - Ritsuka responded before going to sleep.

Answering the reviews I've gotten:

1: There's only 1 Illya and it's the Caster one, I messed up and accidently wrote her name twice, but alredy corrected it.

2: Ritsuka's excuse to the powers used by the Servants can be seen in Chapter 5.

3: Yes, things will be changed down the line because of Chaldea's presence, but for the moment they limit themselves to be helpers to the soldiers of the Walls.