Appearance:He appears to be virtually identical to Rudra,except that his overall color scheme is the opposite of Rudra's. He is a fairly tall and lean-built being with white skin and hair. His eyes consist of black pupils, yellow irises and black sclera. He also has black nails. While Ichigo wears a standard black Shinigami Shihakusho, his Hollow self wears a white Shihakusho with a black cloth belt. When he is later pulled out of Ichigo by Tensa Zangetsu, he wears the Bankai version of Rudra's Shihakusho, except white. In addition, he dons the horned mask that Rudra possesses in his fully Hollowfied form.
He also has his own version of Zangetsu, Rudra Zanpakutō: In contrast to Rudra's black cleaver with a silver edge wrapped in white cloths, his own Zangetsu is silver with a black edge and black wrapping cloths.
Personality:Inner Rudra's most distinguishing features are his maniacal laughter and psychotic grins. He is brutal, arrogant, disrespectful, and sadistic. Inner Rudra has no name, and his only reason for existence is to take over Rudra's power and body to use it to kill everything and anything he sees. He taunts Rudra as being a weak and unsuitable counterpart of himself, though he relishes the idea of taking Rudra's powers for himself. He battles like a berserker, unlike Rudra, ignoring injuries and overpowering his enemies with brute strength and force. He also protects Rudras body when he is about to die, because if Rudra died, he would too. He also seems to respect Zangetsu's spirit to a certain extent.
Inner Rudra has declared that Rudra is the "king" of the inner world and he is the "horse." Inner Rudra wishes to "take the crown" from Rudra so he can have control over the body and become the dominant personality. After his loss, he states he's willing to allow Rudra to keep the crown for now, but once Rudra "screws up again," he declared he'd make his move again.
When he is merged with Tensa Zangetsu however, much of the Zanpakutō spirit's personality seems to be in effect, making the Inner Rudra much calmer, though he is prone to occasional outbursts similar to Inner Rudra. He even states that he wishes to protect Rudra, contrary to his frequent earlier statements of wanting Rudra's body and power for himself.