During his partnership with Sasori, Deidara usually showed a cool, and relaxed attitude, never losing his smirk even while fighting an intense battle or when being blamed by his partner. However, his personality seemed to change to some extent after being partnered with Tobi, as he would easily get mad at his partner’s childish and sometimes disrespectful behaviour. He also had something of a sadistic arsonist nature, 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, roughly translated as "yeah" or "hm". The latter of which is used in the VIZ version. Deidara also seemed to respect the ideals of others as he allowed Gaara to move the sand he used to protect his village into the desert before kidnapping him, even going so far as to admiringly call him noble.
Deidara referred to his explosive ninjutsu as art, usually quoting "Art is an Explosion!" and seeing each bomb he made to be a significant accomplishment. He referred to his style as superflat, and claimed pop is dead. Deidara's pride as an artist makes him simply unwilling to accept that anything could defeat it, leading to his abandonment of strategy during his battle with Sasuke Uchiha, in favour of tactics that let him show off his art. He was able to recognise stronger opponents like Itachi, although he felt that the Sharingan was inartistic, and despised the fact that he had been enthralled by its genjutsu.
Deidara referred to his partner Sasori as Master Sasori, 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 argued over the nature of true art (Deidara holding that art is what lasts within a moment while Sasori believing fine art is something that lasts for all time). This reflected their individual fighting styles. 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 great respect for Deidara, and frequently called him "senpai". The idiotic front Tobi put up greatly irritated Deidara, who believed that all Akatsuki members should be calm, talking less and acting serious. This in turn results in unintentionally angering Deidara to attack Tobi in a comedic fashion (e.g. blasting him with his explosive clay or strangling him with his legs). But in battle, Deidara puts his issues with Tobi aside to work well with him, telling him to get away when he was about to do a more dangerous attack. Deidara also seemed to have a minor sense of appreciation for Tobi, as shown when he apologised to his partner in his thoughts before he initiated his self-destruction technique.