It's the only feature I'm divided on. If they're feral, can't their eyes be yellow or green or some other color beyond red/blue? At least Lockdown has green eyes to represent his neutrality, and Devastator was described as a monster different from the average Transformer so with him green eyes was fine. But perhaps they were once Decepticons who deserted the war or something. It may be a point of exposition like with Wheelie and Jetfire.
I don't think eye color dictates the faction said character is allied with. And, Slug and Grimlock are the only Dinobots with red eyes we've seen in footage from the film thus far. Also, Slug has an Autobot symbol on his head, so they're Autobots.
Scorn and Strafe have blue eyes, Grimlock and Slug have red eyes, and Slash has green eyes. Besides, Mixmaster was a decepticon and he formed the head of Devastator, you don't remember the truck with the Decepticon headed dog on it pulling up
The Dinobots were around long before either the Decepticon and Autobot factions were formed. Plus Frenzy's optics were blue and Wheelie was red and blue because Mikaela broke one his eyes.
it is always an interesting theory about the optics. But one could also ask about Drift because he used to be a Decepticon and now is an Autobot. I believe his eyes are blue now, did they used to be red? How do they change? Does a medic really have to take out the optics and change them out? It's strange and weird and one that I actually kind of wish would be clarified in the movies (or hell even the cartoon or comics).
Generally while Cons have red eyes and Bots have blue, it not a rule and does not mean that good guys have blue eyes and bad have red. While The Fallen had red eyes, so did the other Primes and they were not Evil so to speak. Brains and Pretender Alice and Frenzy had blue eyes but all were Cons (Brains turning Bot) Wheelie was Con but turned Bot as did Jetfire yet their eyes still stayed red. The Constructicons combined into Devs had Green eyes yet the red Rampage Con that Bee fought had Yellow eyes. Lockdown has Green eyes and while he may not be a true Con he is for sure evil. Drift looks to have blue eyes and he was an ex con. We have not seen Slash "yet" but his promo art has him with Green eyes so he may have green eyes in the movie.
Because their toys did. I think it's great we're getting 'good guys" with red eyes again. Not all of them do, too. Scorn has blue eyes.
The Dinobots have almost ALWAYS have red optics. In at least one mode, usually both. To be honest, Scorn's baby blues are weirding me out.
