This will be a post where I try to organize thoughts on theories on this character from the future arc promo. If you reblog it and add more theories, I may reblog it from you, or I might just update the original with your ideas and give you credit.
Theory 1: Many people are wondering if he could be aged Mikey. @kameroleplay @sweetcharlotte Reasons: 1. He has orange on the top of the head (might be yellow). (noted by sweetcharlotte) 2. He’s short. 3. He has blue eyes. (noted by sweetcharlotte) 4. His skin tone looks about right for Mikey. 5. Some old men get really thin. 6. It’s not really clear if Mikey’s in the other parts of the promo. Reasons it might not be: 1. The shape of his arms and legs. (noted by sweetcharlotte) 2. He looks young rather than old. (noted by @redworld96)
Many are wondering if he could be Donnie and April’s child. @sweetcharlotte @tmntvicky redworld9
Reasons: 1. He looks young (noted by Reddy and sweetcharlotte) 2. He’s standing near (and being protected by?) Donnie or the new Metalhead. 3. He might have ginger/strawberry blond hair (noted by Reddy) 4. He has blue eyes like April’s (noted by sweetcharlotte) 5. If you look closely, it looks like he has glasses. (noted by sweetcharlotte) Eyesight issues can be hereditary, and if you recall, April had glasses her freshman year of High School. It’s possible she wore contacts throughout the series, and it’s possible her child would need glasses or contacts, too.
6. He’s wearing a yellow ribbon thing on his right wrist (noted by me and then sweetcharlotte). Sweetcharlotte also mentioned him wearing a purple ribbon thing, but I can’t see it. Not denying it, though.
7. His physique is a combination of Donnie’s and a human’s. (noted by sweetcharlotte) I find this particularly interesting, as I’ve imagined what April would look like if she mutated into a turtle (I know she’s immune to mutagen, but the mind wanders). I imagined her having more human-shaped arms and legs (for example, having defined wrists, and calves and ankles instead of cankles). This is quite similar to the limbs we see on this character, who may have more human DNA. Reasons it might not be: 1. He looks really young. This arc takes place 50 years in the future, and this character looks younger than Donnie and April in the rest of the series. That would mean that Donnie and April had him over the age of 50. He could be their grandson… but then who would their child have had a child with? 2. Could still be old Mikey, or someone else entirely.