Soundwave × Shockwave

Absence of a face: Shockwave has no mouth, nose, or usual eye sockets. His head is a sealed hexagonal or angular helmet.
One eye: At the very center of his head is a single large round photoreceptor (a monocular sensor). It usually glows bright yellow or red. This empty, unblinking stare creates the image of a merciless computer.
Antennae: On the sides of his head are two short antennae resembling "ears," which serve as sensors.

2. Body and color scheme:
   Purple coloration: Traditionally, Shockwave's color scheme is dominated by various shades of purple and violet, diluted with gray and black mechanical elements.
   Powerful build: In most versions, he is depicted as a massive, tall, and broad-shouldered robot. His armor looks angular and durable, emphasizing his status not just as a scientist, but as a dangerous fighter. In the film "Transformers 3: Dark of the Moon," his armor became more detailed, acquiring a gray-steel, ribbed shade and the look of cast fantastical musculature.

3. A weapon instead of a hand
   Astro-magnetic cannon: Instead of his left (in some versions — right) hand, Shockwave has a powerful laser cannon installed.
   Power cable: A thick ribbed hose (energy conduit) runs from the cannon to the robot's back or shoulder, supplying energy for his shots. The other hand remains normal — with massive fingers or claws for gripping.

Alternative form
Depending on the universe, Shockwave transforms into a devastating long-range weapon:
In the classic G1 animated series, he takes the form of a giant space laser pistol.

Personality
Cult of logic
Cold calculation: Shockwave knows no anger, hatred, or joy. Any decision — from conducting a cruel experiment to destroying a planet — he makes based on dry calculations of efficiency. If an action is logical, he will do it; if it's illogical, he will reject it.
Speech quirk: In conversation, he constantly uses the words "logical" and "illogical," justifying his every step with them.

Loyalty to Megatron (through the lens of logic)
Reliable regent: Unlike Starscream, who constantly weaves intrigues for power, Shockwave does not seek to take the leader's place. Megatron trusts him with the most valuable thing — the governance of the entire planet Cybertron in his absence.
Pragmatic devotion: Shockwave obeys Megatron not out of blind fear or adoration, but because he considers Megatron's leadership the most efficient and logical path to Decepticon victory. However, in some comics (such as IDW), if calculations show that the leader is leading the faction to destruction, Shockwave is ready to eliminate him without hesitation for the greater good.
Respect for facts: Shockwave does not despise Autobots or mock them. He acknowledges the intellect of Optimus Prime or the ingenuity of Wheeljack, if they are confirmed by facts.
Ruthlessness: He takes no sadistic pleasure in torturing enemies, but he will kill them in the fastest and most economical way, as soon as they cease to be of scientific interest.

Appearance: A master of disguise and stealth.
Soundwave's appearance is a fusion of retro-classic design and high-tech espionage equipment.
Face-mask: Like Shockwave, he has virtually no human facial features. It is hidden behind a sealed silver mask-plate resembling the Decepticon insignia, and his eyes are hidden behind a monolithic rectangular visor (usually bright red). This makes his facial expression completely unreadable.
Chest cassette deck: Soundwave's calling card in the classic G1 design — a transparent window on his chest where his cassette minions are placed. In more modern versions, this panel has transformed into a drone compartment or a complex tactical screen.
Color scheme: Soundwave's traditional colors are dark blue (indigo), white, and silver, with gold or yellow elements on buttons and armor joints.
Alternative form: In the original, he transformed into a cassette recorder capable of changing its size.

Absolute loyalty: He is devoted to Megatron to the very end, without any reservations. Soundwave is the only Decepticon whose loyalty the leader never doubts. He carries out any orders without question and sincerely despises Starscream for his attempts to usurp power.

Stealth and silence: Soundwave speaks extremely rarely. In the classic version, his voice sounds terrifying — a monotone, deeply robotic computer synthesizer with an ominous echo. In Transformers: Prime, he even takes a vow of silence, communicating exclusively by playing back recordings of other people's voices that he has intercepted.

Information blackmail: Soundwave knows everything about everyone. Using his built-in sensors, he can read others' thoughts, intercept any radio transmissions, and hack any database. Other Decepticons fear and dislike him because Soundwave collects compromising material on them and can report to Megatron about a brewing rebellion at any moment.

Love for his "cassettes": Perhaps the only display of attachment and care from Soundwave is directed at his minicons — Laserbeak, Rumble, Ravage, and others. He treats them like his own pack, and they repay him with unconditional loyalty.

The relationship between Soundwave and Shockwave can be very different — but if you combine everything together, you get something like a cold, silent alliance of two systems.

They are both Megatron's right and left hands. Soundwave is information. Shockwave is science and strategy. They are not friends, not enemies. They are top-tier colleagues. They communicate rarely, on business, in short phrases. Soundwave passes data to Shockwave for analysis. Shockwave proposes a logical solution. There is no warmth between them, but there is the mutual respect of professionals.

Their dialogue is an exchange of minimal words but maximum meaning. Soundwave is silent. Shockwave says only "logical" and "illogical." They don't need long conversations. They understand each other instantly, because both think in systems, not emotions.

Soundwave may watch Shockwave just as he watches everyone else. He knows everything about him. But Shockwave knows this. And it is logical for him to let Soundwave observe, because he has no secrets from Megatron. Between them is cold transparency. No secrets. No intrigues. Only facts.

Both are loyal to Megatron. But in different ways. Soundwave — through absolute loyalty. Shockwave — through logic. If Megatron begins leading the faction to destruction, Shockwave may eliminate him. Soundwave — never. And this creates tension between them. Not enmity. Just a difference. They both feel it. And both stay silent about it.

And if one were to imagine that Soundwave chooses someone to speak to in words rather than recordings — it could be Shockwave. Because Shockwave won't judge. Won't be surprised. Won't use it against him. He will simply accept it as a fact. Logical.