Soundlessinsanity and I LOVE having these bat shit crazy AUs!

In this one, Grisha is messing around with Eren's mutated DNA (the carrier of the Titan Gene), and Marco decides to become a test subject.
Marco is infused with the T!Gene, and becomes a Frilled shark based Titan.
Basically in this AU, Titan Shifters have more animal instincts. Marco is a shark.
Usually he helps Grisha around with chores (he has a smaller titan form, around 9 feet), but also loses himself often and tries to attack Grisha.

Concept of Shark Titan! Marco belongs to me.
Marco Bodt belongs to Isayama