Deidara
Deidara (デイダラ) was the youngest member of Akatsuki, and was partnered with Sasori and Tobi, consecutively, before his death.
Background
Even during his days as a shinobi in his home town of Iwagakure, Deidara garnered high praise for his clay sculptures. However, he still desired to reach even greater heights. At first, he simply focused on creating more and more works, but before long, he started craving a kinjutsu that was passed down in Iwagakure: a technique that allows one to knead chakra into substances.
He violated the law and stole the technique, causing him to be pursued. However, as the Exploding Clay he had used for the first time detonated and took down his pursuers, he saw the art he had desired: the Art of a Single Moment (一瞬の芸術, Shunshin no Geijutsu). Whenever he detonates his Exploding Clay, he recalls the process that allowed him to reach this art.
Deidara caught in Itachi's genjutsu and thus losing his battle.
After he fled his village and became a missing-nin, he started helping insurgents in various countries as a terrorist bomber. This is how Akatsuki eventually caught wind of him. 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 the Sharingan 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 training his left eye to counter Genjutsu.
Personality
Quick to be angered and easily annoyed, Deidara was very hot-headed and often tended to overreact to certain things. Something of a sadistic arsonist rather, he was not above enjoying 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 (...うん, ...un), roughly translated as "yeah" or "hm". 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!" (芸術は爆発だ, Geijutsu wa Bakuhatsu da), was originally coined by famous Japanese abstract artist Tarō 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, at least when he knew he was still able to fight. Yet, he was intelligent enough to recognize stronger opponents. However, he utterly despised Itachi and the Sharingan, believing the latter is not anything artistic, and an insult to his Exploding Clay.
Deidara referred to his partner Sasori as Master Sasori (サソリの旦那, 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" (先輩, senior). Tobi's carefree and goofy personality greatly irritated Deidara, who believed that all Akatsuki members should be calm, talking less and acting 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 appreciation for Tobi, as shown when he apologized to his partner in his thoughts before he initiated his Self-Destruction technique.
He was between his two partners; he was more mature than Tobi, but not as mature as Sasori.
