The Slitheen family do not simply murder their chosen targets; they also convert the corpses into skin suit that they then wear as a disguise. The Slitheen are impressively massive - Rose Tyler once referred to them as "eight feet tall" but thanks to their ingenious, technically-advanced neck braces, these ruthless Raxicorifallipatorians can neatly shrink themselves inside of their victims without hesitation, albeit with a noticeable gas exchange that arouses both suspicion and curiosity amongst their non-Slitheen peers. I've always found this to be the most fascinating behavioural element of the Slitheen family and wondered why they do this, given that it is only allowed by virtue of their neck braces and so is really unnatural to Slitheen evolutionary development? It has become an inherent part of Slitheen culture?
There are many speculative reasons as to why the Slitheen indulge in this behaviour;
1. It enables family business plans to be drawn up - the Slitheen are a tight-knit family of Raxcorifallipatorians who are usually out to make a profit. Unfortunately for their victims, the Slitheen utilise their natural advantages (super size, super strength, advanced intelligence, family networking, capability to acquire advanced technology, and, most importantly, the ability to fit inside their victims) to engage in deceitful, violent behaviour; seeking to pry away economic assets from those non-Slitheen that they deem "enemies". Sometimes, this could be a simple bank heist. Other times, it could mean blowing up a planet and selling its scattered remnants for spare parts to make a fortune on the intergalactic stock exchange in the midst of a galaxy-wide recession. Skin suits are a means to an end.
2. It allows the Slitheen to infiltrate their enemies; accessing otherwise out of bounds spaces, enabling intelligence collecting, identifying threats, strengths and weaknesses, active learning of non-Slitheen culture - all of which help to inform the family business plan. Sip Fel Fotch Pasameer Slitheen posing as PC Strickland in Aliens of London/WW3 shrewdly identified in live, real-time Jackie Tyler as a threat to the family business and sought to eliminate her (sadly unsuccessfully).
3. It offers the Slitheen a way of 'going native'; safe inside their victims, the Slitheen must perform non-Slitheen cultural rituals to fit in with the local scene and not arouse suspicion. The Slitheen that murdered the Stafford humans and took possession of their skins continued to behave as their human counterparts during The Lost Boy Two-Parter, and therefore Luke Smith initially did not realise the danger he was in. Some Slitheen enjoy this element; other family members abhor it. All, however, must perform this on occasion if they are to survive and advance the family business plans.
4. Power & Domination - skinning a victim represents a most awesome violation of norms and decency. It's utterly savage and uncivilised behaviour. That's if you believe in some universal standard of morality. The a-moral Slitheen don't - they create their own morality on the go. The Slitheen, simply because they can, literally convert their targets into personal property and do whatever the hell they feel like inside of them, demonstrating their natural dominance over their victims, which serves as a justification for the killing and subsequent skinning. It's a form of conquest. They will also hunt or mail down anyone who dares to challenge their supremacy. General Asquith learnt his sorry lesson never to challenge Slitheen power again by paying with his life - Jocrassa (presumably; it is never down on-screen) unhesitatingly mauled him after toying with the ordinarily powerful human general, and the Slitheen turned his suit into an important part of the family business plan! Skins are akin to trophies, and making them affirms an inherent, aggressive Slitheen supremacist outlook against their vulnerable victims. They also allow the Slitheen to engage in the most deceitful behaviour possible as their non-Slitheen peers are generally unaware that a member of their species has been killed and turned into Slitheen property. This allows the family business operations to continue unimpeded.
5. Element of surprise - Once a Slitheen family is able to infiltrate very far amongst their victims, it is very difficult to stop them. They can easily hunt and skin more victims once well placed. If attracting suspicion or even become accused of something devious, the Slitheen simply unmask to turn the tables back into their favour. The Janine Slitheen is a prime example of this when being constantly questioned by a probing Sarah Jane Smith during Revenge of the Slitheen. She got fed up and simply unmasked to try and deal with the situation. Often, their victims are unprepared for this and the Slitheen usually kill them, if not immediately then surely after an impromptu hunt. You have to be exceptionally lucky to survive a Slitheen encounter…
6. Fun - The Slitheen generally find their victims to be stupid, pathetic and inferior. That said, this does not stop them from indulging in Funtime when hiding inside a skin. The disguised Slitheen will readily assimilate into their victim's culture and enjoy all the pleasures available to their skin suit according to their social status, wealth, proclivities etc. The Slitheen adult that poses as Oliver Charles felt somewhat sad that he had to wear General Asquith, claiming that "God, I was busy" with Oliver's human wife, mistress and "farmer". The prospect of getting together with other disguised Slitheen members and unzipping and stripping together before a hunting activity further enhances the fun element. It's all mutual pleasure and makes the whole ordeal of wearing disguises totally worth it in the end.
7. Protection from acidic substances - technically, a skin suit functions as a layer of clothing on a Slitheen individual. Whilst some may loathe having to wear a disguise, all recognise that it offers some protection from acidic substances that could drop onto their otherwise naked calcium-based bodies and cause them to blow up violently. Going naked all the time is unwise, especially in hostile environments - the Slitheen family recognise that by wearing a suit.
8. Erotic element - Many Slitheen relish their sexuality. They are unabashed about this, especially in front on non-Slitheen. Blon Fel Fotch Pasameer Slitheen enjoyed "shaking her booty" when safe and snug inside of MI5 Agent Margaret Blaine. And the sexy behaviour associated with this speech was shamelessly conducted in the presence of a human general (Asquith). Being inside a victim is so intimate, and this is probably augmented by the tightness and chafing that many Slitheen have to suffer from when in disguise. Many Slitheen also take on the sexual mores of their victim's culture to better fit in (the aforementioned Oliver Charles Slitheen example comes to mind once more). It links again to the notion of power and domination as well, given that the Slitheen can now access more and newer experiences and resources that their disguises offer them. Some Slitheen enjoy emitting the gas exchange in an overt sexual manner. Perhaps that serves as "compensation" from having to suffer from chafing inside such tight clothing?
9. Unmasking - all Slitheen enjoy returning to their innocent, natural state of being, that of nudity. Slitheen are generally excited to be able to unzip their foreheads; usually smiling, laughing, groaning and moaning when doing so. They love to unzip in front of their enemies if it is safe to do so - surprise! It's the one occasion where a Slitheen is happy to end the deceit and reveal the true nature of what is really going on. To see them paralysed in shock, horror and fear only adds to the excitement. Slitheen love to announce who they are to their intended victims. Other times, especially if a Slitheen is isolated and begins feeling lonely, they may retreat to a safe spot and unzip to make themselves feel better (Blon Fel Fotch expertly displayed this behaviour early on during Boom Town).
10. Mockery - the Slitheen usually detest their non-Slitheen counterparts. Because they often have to disguise themselves as members of a non-Slitheen species, the unnatural and forced clothing usually gives cause for impatience and resentment. Luckily, the disguise gives a Slitheen free license to mock and curse his surrounding peers without repercussions or anyone not a Slitheen understanding. Oftentimes, Slitheen will also utilise the gas exchange to mock their non-Slitheen counterparts: the Pasameer family did this to devastating effect when being lectured by the unfortunate General Asquith. Their persistent farting not only mocked but actually undermined the human's authority. Another good example is when Jocrassa farted whilst posing as acting Prime Minister Joseph Green in front of the Doctor to toy with that smart individual.
11. An inhibited sense of guilt - this is counter-intuitive and more linked to the subconscious. I believe that a lot of Slitheen who regularly engage in hunting and skinning feel that they need to compensate for stealing the lives of their victims by living the lives of the victims for them. Blon Fel Fotch expressed this powerfully as Margaret Blaine to the Doctor during the episode Boom Town ("God, I've gone native!"). In her daily routine as a human, Blon identified as Margaret unapologetically, she accepted this reality. Jocrassa meanwhile murdered Joseph Green and turned him into a suit, but he managed to get Green to the top of UK government, something that that lowly human most likely would never have achieved should he have continued living. The Slitheen posing as General Asquith truly gave that body a driver capable of commanding other humans with the uncontested authority that the Slitheen exposed as worthless when they killed the human. Perhaps if a Slitheen goes a long time inside one skin, they will end up identifying with it. This explains why they are so confident and arrogant when impersonating their victims in the presence of non-Slitheen, despite their mistakes, mishaps and off-putting behaviour. That said, they are not remorseful about the killing and skinning as they believe themselves to be superior predators with a natural right to do whatever the hell they like to their victims.
12. A sense of meaning - what's a Slitheen without a skin suit? Skinning aggressive competitor enemies of the family, or just simple innocent victims identified during family business planning time gives the Slitheen a sense of pride as well as purpose. Slitheen culture is violent and organised around the accumulation of power and wealth. If you do not skin and wear a victim should be the family collectively decide that serves the family business, you will most likely be censured and even be killed by your own family to serve as an example to other members what happens when you fail to embrace your Slitheen upbringing. The Child of the Slitheen kills the humans Carl and Gus and obviously makes skin suits out of them. At such an early age, it allows Slitheen minors to participate with their adult counterparts on serious missions thereby fulfilling an educational role.
13. Desperation (?) - some Slitheen may not intend to kill and convert an unfortunate victim intentionally. However, if they crash land on a hostile planet, or are on the run from the Judoon or other competitors who temporarily have the unfair advantage, Slitheen may decide that skinning and wearing a third party species may be the best way to take off the heat and offer respite for a while. It may sound unfair but a Slitheen must survive ahead of others and if that means innocents die, so be it.
This is my analysis explaining both why the Slitheen skin and wear their victims as well as helping me to understand my own fascination with this awesome family of fearsome predators. Do you have anymore? Let us know in the comments!