I warn you.... big big spoiler ahead......
The big big spoiler is.......... I found out how the Titans were created........
Yeah...... So any way..... I was thinking really hard if I should tell you the spoiler or not because I didn't want to spoil you guys, but since some of you said you won't regret it....... then here it goes .....
Here's the last chance to back out....
Eren's dad Gresha when he was younger lived outside the walls. There were actually cities with blimps, tall buildings, and stadiums ( Not as modern as now though). Geisha was about 14 and his little sister was about 8. They liked to watch the blimp as it flew in the sky across thier house and decided to follow it. Their mother warned them to be careful of the dangers they could get in to, but they were still carefree and left. They followed the blimp all the way to where it landed, which was too far out from their territory. Soldiers stared to to talk to them a bit harsh and told Gresha to leave and go and they would've brought his sister home from him. But she didn't come home. The soldiers actually feed her to their vicious dogs and throwed her body away. They didn't confess, though. They lied to Griesha's parents. His parents didn't belive him when he tried to tell them that they killed her. From that day on he vowed vengeance on those soldiers and created a secret group. One day a girl was brought into their secret hideout and was said to be part of the royal family. She and Gresha eventually fell in love and had a child. That child was Zeke. Griesha had great expectations for Zeke, but in the end, he snitched the existence of the group to the officers. They were captured and was given an injection. The soldiers then pushed them off the wall. As they they tumbled against the wall drawing blood they transformed into titans. Griesha wasn't a normal titan though, he was smarter than other titans. He ate Historia's sister who possessed the coordinates giving him the opportunity to regain human form. He then was found by the trainer of the cadets and was brought inside the walls where he met Carla and had Eren. So, after the breach of Shaganshina, Greisha gave Eren an injection making Eren transform and ate him giving Eren the coordinates. So basically, titans were created by a type of serum that could gentically mutate a being making them dense for almost everything except for the thirst of humans.
So yeah, that was the Big Bog spoiler...
Sorry if its not as big as you expected
And if it is then I'm really really sorry!!!