A manga about two boys originally from an orphanage First, I want to inform that I'm French, so I'm sorry for my bad English... 

I'm desperately looking for a manga that I can not manage to find despite all my efforts. On the dozen forums where I was searching, I found nothing. I remember only few scenes of the story:


It talks about two boys in an orphanage who plan to flee when one of them is going to be adopted. But in the end, they are taken together.
Some years later, they are in a kind of army. For a reason that I don't remember anymore, one of the boys escaped from the organization and hid himself among the society, where he attended high school.
But one day, his old friend is ordered to get him.
I read it around 3 years ago. One of the boys has black hair and seemed to be cold with others. And I think the second boy was blond.


Here's all I know, I hope that I've been understood. 

Thank you in advance!
Oh, I finally found it! It's Aegis. Someone just told me the title on a forum. I also mixed some parts of the story with another, sorry. Thank you again for your answers.