Small info dump about the Cosmic 'Twins' in this.
Unicron:
Okay so uh. Unicron is... Something alright. God of chaos, destruction, hunger.. You name it. But lately he is just... To lightly put it, a literal lump. He doesn't do much at all for what he is. He sleeps most of the time, one might say he's like a lazy dog. And the so called "owner" of the dog, if we may, is none other than Megatron.
If Unicron was to be out in the physical world, there is a literal leash if we could call it like that, that Unicron has. Best said it's a chain leash he has, and yes only Megatron gets to hold it and have total control of Unicron. There are times where it's off, and it's not that often, since I think it makes sense why, considering this is Unicron we are talking about.
Another thing I'd like to state about him I'd that his horns are VERY sensitive. He broke them once himself with his own hands, one grew back while the other didn't completely and it can also occasionally hurt. Overall, we can say that his helm is a "very weak and sensitive spot".
Instead of a planet (or how some things have it, the Earth itself) he is a dragon in this, [transforms into one]. And in the robot mode he keeps the tail and to say the least it's expressive, and so are his wings. He actually has 4 wings but they are useless really since he cannot use them to fly with the fact they are like skeletal, one might say they are just for the show or to look more intimidating at best. Though for being a God he still can fly or hover above the ground anyway. He is also flexible overall... We don't ask why. He is just very special like that. (•ᴗ•)... Can't forget to mention he is NOT a Titan. Or at least, he chooses his size, but still makes himself somewhat taller than others to appear more "superior" than them. But he is still a big nuisance either way no matter what..
Primus:
The situation is similar as it is with Unicron and Megatron. But it's with Optimus for him. And there is no "leash" for him.
Primus in this case doesn't transform at all. Nor is he Cybertron. Well.. It's his different unconscious form, to put it differently. And he is MUCH different than Unicron. He doesn't sleep or eat like the Chaos Bringer does. He can but simply doesn't want to. And generally he is more chill than Unicron and his silence is more terrifying than Unicron's constant threats he may come up with. And it's the same as Unicron for the sizes, though instead of "superiority", Primus just likes being tall but not taller than Unicron.
Primus himself has wings, not like Unicron's obviously but it's best described as "angelic" wings but metal obviously.
Like I said, he is more chill. A little.. Too patient for his own good. But to be fair he IS the God of Creation. And unlike Unicron he genuinely doesn't feel pain at all, or he is just good at hiding it well because he shows no reaction about anything.
We could say he is... The not well paid therapist but has enough patience to help anyone at any time he wants to just because he can and has the patience of a saint.
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just one of their interactions
“ Do you do something else besides sleep and eat all day? It rather seems.. Boring. ”
“ Boring?! That's a new one to hear, even from you. ”
“ I don't see the point of wasting life doing whatever that is you're doing. ”
“ Complain all you want to, at least I know how to enjoy it. Or do you prefer it's war again? ”
“ I'd prefer to snuff your anti-spark from the face of this universe. ”