Never change a thing

Explanation

It was night and the Levi squad,the shifters and commander Hanji were gathered in a room.
"So,i think it's time that you explain to us this whole Titan abilities story and YOU about your relation with the Armored and the Colossal Titan"said Levi pointing out at the shifters and then at Annie.
"Well the only thing that i know is that my father gave me this powers"said Eren looking down.
"I was a little kid when i first became a mindless titan,it was a punishment for something that i did,I don't remember a lot but i do remember that people used to treat like a queen with the name Ymir.After that i was a titan for 60 years,it was like a never ending nightmare,until one day i ate someone and *poof* i was human again."said Ymir looking down sad remembering her past.
"You mean you were like Sonny and Bean for 60 years!"said Hanji full of excitement.
"Yes"
"Now its Happiness turn to explain everything"said Levi looking towards Annie.
(Spoiler alert for not Manga readers)
"I guess that i should start from the beginning of everything.
*Annie sighted*A long time ago there was this person who in some way achieved titan powers out of nowhere,it was the founding titan,after 13 years that person gave its powers 9 every shifter has 13 years to live until there body weakens and they die but back to the story,after that the great Titan war took place and the 145th Marlian king inherited the founding titans powers and with those powers moved his people away from war territory to this land,now in the year 845 me,Reiner,Bertholdt and one other person we're sent here from Marley our home country outside the walls to retrieve the founding titans ability and destroy humanity*Annie started to cry*i'm sorry for everything wrong that i've done for all the secret's that i have kept."
"Who was that 4th person you talked about?"asked Levi.
"His name was Marcel he had titan abilities to,but as soon as we got here he got eaten and i think Ymir here ate him."
Ymir looked shocked at Annie's statement.
"Don't worry if he was still alive he would have a pain in the ass"said Annie to Ymir.
"I guess that now that's everything we've got"said Levi.