Long seen as one of Batman's most intelligent villains, Nygma is characterised by what has now been written as a compulsion to leave a riddle, stemming from a long stream of childhood abuse, both physical and mental. His father, a less than cognitive man, was jealous of his son's superior intellect and would vent his frustrations through a physical admonition of the young Edward to "tell the truth".
This, along with being awarded a riddle book as a prize for completing a puzzle - in which he cheated to ensure his victory - formulated the idiom which would eventually become his major alias.
The issue of his surname, variously Nashton and Nigma / Nygma, has been addressed by his name having been legally changed to the various scripted Nigma / Nygma upon leaving the small pickings of normal criminal life and entering into the Gotham City arena.
Beginning as a profiler and informer, he would help the underworld, including Batman himself, by providing information and insight, before establishing himself as a notable criminal within his own right.
The major events for the character are his development and subsequent curing through a Lazarus Pit of brain cancer, which evoked an epiphany within Edward, revealing the identity of Batman.
In a poignant, if perhaps unintentional mimcry of his original backstory, Riddler is then humiliated and beaten by his peers once again, becoming introverted and furthering his insanity, ending up as one of the many homeless on the streets of Gotham.
After another rebirth, this time from a codebook rather than a pit, he returns to an impressive form against the Green Arrow and Aresnal. His predictable imprisonment after this is once more disrupted as the Secret Society of Super Villains arranges a global breakout - which culminates in his being hospitalised by Shining Knight, comatose for a year.
This fall and rebirth cycle continues when he awakens, but this time, there are some facets cut differently.
His compulsion for riddles is gone, he has amnesia, possibly retrograde amnesia, but establishes himself once more as an informer and profile, completing the circle of his life in Gotham.
His role as a detective in this manner had him working alongside both Batman and Nightwing, deducing Grayson's identity whilst harbouring a suspicion towards Bruce Wayne.
Since then, he had been held in a torpid state by Poison Ivy, who, along with Harley Quinn had been using his rooms as a hideout. Brought out of this by a villain out to make a name for himself by killing Catwoman, he begins to show signs of slipping by beating the already downed villain viciously with his ?-cane.
Still continuing as a law-abiding detective, he saves the life of a woman, collaborating with Batman and earning some small measure of trust, although Batman is still dubious.
Whilst conducting more detective work, Edward's face was marred by an explosion, which prompted him to use his old domino mask and reawoke his dormant psychoses. After being used and betrayed once more by Quinn, Ivy and Catwoman, he begins to ruminate over returning to his criminal ways, eventually stepping back onto the crime scene with Enigma, his daughter, who it is indicated he later kills.
His powers, such as they are a reasonably unknown talent for escapology and an incredible intellect, knowledge and deductive process - he was able to deduce through purely mental activity, something which Dick Grayson required both Alfred and the Bat-Computer for.
The constant, near phoenix-like, cycle of rebirth which has defined the character - more so than usual, as it unusually repeats along much the same lines each time - identifies Edward / The Riddler as a man not so much bad as unguided.
Betrayed time and again, out-muscled rather than out-brained by those who would be considered family - a stretch admittedly, for the other villains - he has forever held the sanctity of truth paramount. His riddles are a way to deal with his compulsion towards honesty, whilst still satiating his undeniable psyche, as his id, ego, and super-ego can all be seen manifested in his crimes, an incredible focus of being. This has led to his introversion, and more cerebral approach to crime, and placed him in something of a second-tier on the criminal scale.
His mental capacities are undeniable, and often sought after by others, but his lack of brutality, or finite violence has lowered his standing. This can be considered quite wry as Riddler has often deviced quite inegnious, if not sadistic ways in which he can have his victims kill themselves.
His general character portrayal has matured over the years, but he still remains a somewhat fey character. I have however, yet to encounter him in the new 52, so consider this to refer to the previous workings.
