When the letter comes in, Leo is the one to see it.
There's no return address, nothing on it to give away where it's from, but Leo would know the surprisingly elegant hand writing anywhere.
He drops the rest of the mail on the closest flat surface and runs for his family yelling at them all to come here. They scramble inside, weapons out, but Leo doesn't pay any attention to that, he's ripping open the letter and yelling that it's from Mikey.
There is silence and stillness for all of half a second before there's a mad scramble to get at the letter.
It gets to the point that Splinter simply snags it from Leo. "If you do not stop, you will rip your brother's letter, and I would like to read it."
All three of them are sheepishly silent and still as their sensei and father reads the letter from Mikey aloud.
Hey guys.
I know you're all kinds of angry right now. I don't blame you.
"Shell yeah we are, you stupid meathead." Raph's voice is tense as he mutters the interruption, his brothers all making sounds of agreement before Splinter hushes them so he can continue.
I needed this though, I needed to do this, and I didn't want you to stop me from going.
I love you all, I promise I'll make it home to you, even if you aren't very happy with me when I get there. I'm sorry I left without saying anything to any of you. I'm sorry I only left a note. I'm sorry I made you all panic before you found the other note. I'm sorry this probably really hurt all of you. I'm sorry for all of that, but I'm not sorry that I needed to do this for me.
The room is silent, all of the turtles shifting and glancing at each other as they absorb what their littlest brother is telling them. "Did we…did we miss something?" Donnie's voice is soft and worried. "Did we miss signs that Mikey was hiding? Did I miss them?"
Splinter pauses in his readings to comfort the brothers, all of which look worried and guilty. "No my sons. Sometimes, a spirit can be happy and content without peace. Michelangelo was happy here, of this I am sure, it seems he just needed to do this and find something for himself that he could not find here. This does not mean you were bad brothers, or I was a bad father, it does not mean that he was unhappy or we missed signs, it just means that Michelangelo could not find what he needed here." He waits until his words seemed to have calmed his sons some before continuing.
I'm learning a lot out here though.
Leo, Raph. You guys are gonna love some of this stuff. I'm learning some things to expand on my shell-kicking skills for hand to hand and weapons, I've got a lot of stuff to show you, and I'll have even more when I'm done.
Raph and Leo go still as their brother addresses them, listening intently and muttering to themselves about 'egotistical little brothers.' Both of them are happy their brother is addressing them even if they aren't happy with what he chose to do.
Donnie, I didn't forget about you bro! I thought you'd appreciate the fact that I'm learning some awesome first aid stuff out here more than anything I had to say about my fighting. I've always worried about you being the only one with any medical know-how for any of our spectacular accidents on hand, and now I'm learning some here so you won't be the only one! I'll make sure to teach you this stuff too okay? We can trade!
Donnie looks up from his toes as Mikey addresses him, his eyes widening with surprise. "He's…learning first aid? And…he'll teach me when he's back?"
He glances around at the others, all of them equally surprised Mikey is somewhere sitting still long enough to learn to fix someone, and that he was offering to sit still long enough when he got back to teach someone.
He pauses again as the last bit registers "He…wants me to teach him more when he's back…?"
Sensei…Father. I'll make sure to share everything I learn with you when I come home okay? I know you're probably not happy with my choice to leave without any word or hint to where I am or where I was going, but I really did feel like I needed this.
Splinter pauses long enough to sigh and address an absent Mikey "I will be waiting, even if I wish you had not left without a word my son."
Tell Casey and April I'm sorry I left without saying anything and that I'll come back okay? I'll have some stories for them too.
I love you all, and I'm sorry I didn't leave you any way to get ahold of me here. I'll contact you guys whenever I can. I'll see you all again. Ninja Promise.
Love you.
Mikey.
PS. You guys better be taking care of Klunk and my Comics!
The brothers all draw in a breath at the sight of the Ninja Promise. It was something they had done when they were younger. Mikey had started it. It was the brothers' version of a word of honor between themselves. Something never to be broken. Something they only used when they really meant what they were saying. Mikey had Ninja Promised to see them again and contact them when he could.
It was a relief to them all. It solidified the idea that Mikey was coming back, that they would see him again, that they would continue to hear from him in their heads.
All of them snorted on a laugh at the sight of the PS. It was just like Mikey to make threats over his cat and comics.
The brothers place the letter into a large orange shoebox and put it on Mikey's desk where they could all get to it whenever they wanted.
They take to writing replies to all the letters Mikey sends them even if they can't give them to him until he comes home.