The Affront are a species described in Excession. Originally named after their homeworld Issorile, their current name was given to them by another Involved (at the time) species - the Padressahl - after they ate the members of a Padressahl trade mission to Issorile. They embraced their given name, proud of their exuberant sadism.
An average adult Affronter's body consists of a floating, bulbous mass about two metres in diameter, which hangs from a frilled gas sac one to five metres in diameter depending on their desired buoyancy and which can be deflated and covered by protective plates.
Six to eleven tentacles of varying length and thickness grow from the central mass, of which at least four end in leaf shaped paddles. Many affronters have lost one or more tentacles in combat or duels. Beaks on the front and rear of the central mass cover the creature's mouth and genitals, respectively. The eyes and ears are held on stalks above the fore beak (they also have a sensor bump atop the gas sac). An anus/gas vent is located in the bottom centre of the main body. The latter is one of their sources of propulsion, though they usually 'walk' on their limbs or 'paddle' through the air unless in a hurry.
Their homeworld is described as a 'fog-bound moon-planet', probably similar to a larger version of Saturn's moon Titan. Affronters require a high pressure, low temperature environment, and breathe an atmosphere composed mostly of nitrogen and methane, plus other trace hydrocarbons.
The Affront became a major galactic species - of a power and advancement sufficient enough to prevent too direct an intervention by the Culture - by virtue of several coincidences. Discovered by the Padressahl, a much more powerful species at that time, they proved impervious to the Padressahl's Culture-like attempts to change their predatory outlook towards other species, or to change their sadistic nature. When the Padressahl eventually sublimed, the Affront were advanced enough to start expanding widely from their local sphere of influence, which by chance lay on the other side of the galaxy from the Culture. By the time the two civilisations came into closer contact, shortly after the Idiran-Culture War, the Culture was not willing to entertain another massive military action to contain the Affront (even though it was at the height of its military power). Clandestine efforts to moderate their society did however continue, and after the Affront's warlike actions in Excession, the Culture started more direct steps in limiting their expansion and behaviour.
Affront society is described in Excession as being "a never ending, self perpetuating holocaust of pain and misery", where the strong prey upon weaker species and individuals. The Affront therefore pose a difficult moral problem for the Culture with its reluctance for direct intervention. However, the Affront are intelligent and cooperative enough (ritual or spontaneous duels notwithstanding) to build a stellar empire, and to develop advanced technology, or else steal it. They have also received some Culture technology (such as the ability to build orbitals) in exchange for grudgingly kept promises of better behaviour.
Among their own technological accomplishments is a strong aptitude for genetic engineering, which they developed long before spaceflight. They use this skill almost exclusively on 'prey species', which tend to be changed so as to provide greater sport (and opportunity for sadism) during the communal hunts forming a major part of the Affront culture. One of the few changes to their own species was the redesign of their females to make sex painful for them, a choice exemplary of the reasons they are considered abhorrent by the Culture. While the main (human at least) protagonist of the book agrees that these qualities themselves are odious, he also admires the Affront for their energetic and "risky" lifestyle, glad of an alternative to the Culture's excruciating politeness, and even speculatively wishes to become one of them at least part of the time.
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