Deidara was originally from Iwagakure, although he readily abandoned the village for the opportunity of using his "art" more frequently, as his village ridiculed him for it. Deidara became an assassin bomber for hire, not caring who he worked with as long as he could use his artwork.
Sometime after Orochimaru left Akatsuki, Deidara was located by Itachi Uchiha, Kisame Hoshigaki, and Sasori, who were under the orders of the leader, Pain, to recruit him. Deidara refused at first, resulting in Itachi challenging him, promising to leave him alone if Deidara won. Deidara willingly accepted Itachi's challenge, but was easily defeated by Itachi's Sharingan, and joined the Akatsuki. Deidara, having taken a huge blow to his ego, carried a murderous loathing for Itachi and other Uchiha for the rest of his life, although he was intelligent enough to recognize Itachi as a more powerful opponent. However, he did take steps during his time with Akatsuki to get revenge on Itachi, such as taking steps to counter Genjutsu.
PersonalityQuick to be angered and annoyed, Deidara was very hot-headed. Something of a sadistic arsonist, he was not above relishing a good fight, and he often blew up his opponents in a very brutal fashion. Deidara's most distinctive trait, however, was his love of art. He would respect any form of it, even if it disagreed with his own. Deidara also had a habit of ending his sentences with nasal-like grunts, roughly translated as "yeah" or "hmmm". The latter is used in the VIZ version.
Deidara referred to his explosive ninjutsu as art, believing each bomb he made to be a significant accomplishment. He referred to his style as superflat (referring to certain types of art), and claimed pop (another art style) is dead. One of Deidara's catchphrases, "Art is an Explosion!" (Geijutsu wa Bakuhatsu da), was originally coined by famous Japanese abstract artist Taro Okamoto (several of Deidara's explosives have resembled Okomoto's works too). Deidara was very proud of his art, to the point that he was simply unwilling to accept that anything could defeat it, leading to frequent overconfidence in battle.
Deidara referred to his partner Sasori as Master Sasori (Sasori no Danna; English TV "Sasori, my man"), out of respect for him as a fellow artist. He also admitted, at least outwardly, that Sasori was more powerful than he was. In spite of this, Deidara wasn't above goading his partner, and they frequently squabbled over the nature of true art (Deidara holding that art is transient and departing quickly; Sasori believing fine art is something wonderful that's left long into the future). This reflected their individual natures (Deidara made clay sculptures that exploded; Sasori made long-lasting puppets out of humans). Deidara outwardly seemed to respect Sasori's beliefs, but couldn't resist getting a final jab in after Sasori's death.
Deidara's partnership with his second partner, Tobi, however, was very different. Tobi apparently held a great respect for Deidara, and frequently called him "senpai" (senior). Tobi's carefree and goofy personality did not please Deidara, who believed that all Akatsuki members should be calm and serious. Tobi frequently and unintentionally angered Deidara, which usually resulted in him attacking Tobi in a comedic fashion (e.g. blasting him with his exploding clay or strangling him with his legs). In battle, however, the two quickly set aside their differences, and worked well together. Deidara also seemed to have a minor sense of respect for Tobi, as shown when he apologized to his partner in his thoughts before he initiated his Self-Destruction technique.
