Due to its highly successful first season, there has been so much clamor from fans for the upcoming "Attack on Titan" season 2 to be released. Even though confirmation of the upcoming season has been announced, not much has been said about the season's upcoming plot.

Many speculations have surfaced online, most should be taken with a grain of salt, but there are two things that has constantly been popping up on different sites. First is that Dr. Yaeger's mysterious basement will be finally explored and the second one is that Eren and Zeke are actually brothers.

The manga version of "Attack on Titan" has already tackled the exploration of Dr. Yaeger's basement. It apparently contains his secret journal which was discovered by Eren along with the Survey Corps. One of the journal contained a photo that pretty much answers a lot of questions, at the same time, gives rise to a lot more.

It was reported by iTech Post that this discovery is ahead of its time since the technology is not part of the world they are in yet. This has led to the idea that Dr. Yaeger may have been from a more advanced community.

The exploration also led Eren and the Survey Corps to find out the truth behind his family. He discovered that Zeke is actually his brother. Zeke has already been introduced in the first season as a powerful being that was responsible for the death of Commander Erwin Smith.

He is also able to transform into a Titan while still retaining is human mind. Not much has been tackled about his history and how he obtained his power but it is expected that "Attack on Titan" season 2 will tackle that.

Game N Guide also speculated that Mikasa will get jealous over Zeke. Further more, they had also reported that Zeke and Eren will have a battle even after finding out that they are brothers.