The Sontarans are bred for war, cloning vast numbers to continue the fight against the Rutan Host. Each member of the species is a soldier much like the Cybermen. It obvious to see the parallels between the militaristic species.
Could their outlooks forge an alliance between the two races? The Sontarans already make use of battlesuits, it wouldn’t be a stretch to see them using cybernetics to gain an edge in their fight against the Rutans.
In return the cloning technology would greatly benefit the Cybermen. Never again would they need to worry about dwindling numbers. One reason that has been given for the Cybermen having so few numbers is that their conversion process only works on human or human-like aliens.
Even if we accept that the Sontarans aren’t prime candidates for conversion the cloning technology still only needs human DNA. The Cybermen could either use what remains of their organic material or simply capture human donors.
This could be the start of an adventure, with the player characters hearing about people being kidnapped rather than converted by the Cybermen. Investigating what they need the people for the player characters could track them down to a Sontaran cloning factory, new human clones being ‘hatched’ and immediately converted in a never ending assembly line.
In the long term both races would know they would come into conflict at some point but the universe is a big place. By the time that they are the only two species left both would be arrogant to think they could deal with their rivals.
The Rutans provide an excellent excuse to get the two species involved with each other. If one or more Rutans could replace some Cybermen then the Sontarans could come hunting for them.
Would the Cybermen perceive the Sontarans actions as an attack? Would they believe that some of their number had been replaced and if they did would they co-operate with the Sontarans, using their experience with the Rutans?
Player characters might arrive in the middle of this situation. They can influence events to either aide or hinder one or more sides of the conflict. Will they help find the Rutan and risk a lasting alliance between the species or will they enable the Rutan to wreck havok by eluding capture?
THE GREAT INTELLIGENCE
This entity from another dimension can possess living beings and makes use of robots. What if the Great Intelligence decided to work through the Cybermen, hoping to use them to conquer the Earth and allow it to manifest?
If it could possess a Cyber Leader then it could command the Cybermen to do anything. Using its expertise in robotics it could order a redesign in their structure, perhaps developing Cybermen/Yeti hybrids.
The Great Intelligence’s Yetis were powered and controlled by metal spheres. This could form a back-up system in the Cybermen, should their organic components fail. Imagine the surprise and horror that would occur if an apparently incapcitated Cyberman, whether it be due to exposure to gold dust or beheading, suddenly got back up. They would initially appear to be ‘zombie’ Cybermen, until the extra power source was discovered.
The player characters might witness a surprising change in tactic from the Cybermen. With the Great Intelligence in charge they have a better understanding of how to inspire fear and worship.
They might develop cyborg monsters and form a cult, loyal members undergoing conversion. Resources would be spent on arcane technology, designed to breach the dimension bridge and bring the Great Intelligence across.
In this scenario the player characters could try to bring the Cyber Leaders strange behaviour to the attention of the other Cybermen. If they could be made to realise that they have been compromised by an alien intelligence they might be persuaded to rebel.
This combination introduces a sense of the occult to the Cybermen, something that contrasts with their scientific nature. An encounter with the Great Intelligence also opens them up to the existence of things beyond their understanding, something which they can’t convert.
Plastic Cybermen. In addition to being a cool name for a band this has a lot of possibilities. Firstly both races want to conquer the universe but desire very different things. The Autons are interested in synthetic material the Cybermen would be interested in the organic components and minerals.
This means that an alliance between the two is entirely possible. The Cybermen can’t offer a lot to the Autons but that shouldn’t matter. By providing living plastic to the Cybermen they need far less material to produce agents.
There are many reasons why the Cybermen might use plastic instead of metal. Although it might not provide much protection from weapons their outer covering could have a limited amount of sentience.
This would allow their outer shell to shift and change, adapting to the situation. It could be shaped into a melee weapon, stretch think to allow them to glide, form into tentacles to entangle opponents or become a tool to aide the Cybermen.
In many way this would be a symbiotic relationship. The Cybermen would be freed of the limitations that metal bring while the Autons would have agents who could still operate even if the Nestene intellgence was blocked.
When visualising these Cybermen/Auton hybrids I imagine them to be cream or beige in colour. Something that would highlight their plastic nature, making them markedly different from the Cybermen in silver.
A conflict between the Cybermen and Autons would be fascinating. Both sides abilities to vary the form of their soldiers could lead to some extreme redesigns. The arms race between the to could escalate to the point where combatants appear completely bizarre.
To give the player characters an interest in the outcome there should be an innocent third party caught up in events. Just as an example the Cybermen could be attempting to invade an Auton held world, in order to convert the planets original inhabitants.
If the Cybermen win the people will be freed only momentarily before the Cybermen convert them. If the Autons win then the people are still slaves. The only good outcome would be for both races to wipe each other out.