Ruku would be perching in a small dried out dead tree in the white sandy wasteland of Hueco mundo. He didn't have much on his mind put to gain power. He did not want to work under any authority but he may have no other choice in order to gain strength and concur more abilities to become an arrancar. Being a hollow wasn't the best of survival, most hollows get defeated simply however Ruku was quite the significant hollow of Hueco mundo. Many hollows have feared him due to his two abilities he possessed.
That was mockery of things including voices. Out of loneliness Ruku would whistle out into the abandon desert to keep himself entertained since most hollows avoided him. Listening to the echos of his whistles, would perk a small smirk on his beak showing his content of his own echo. Suddenly since he had whistled out in the middle of no where a hollow would roar. Ruku would assume the hollow didn't know who he was and what he is capable of doing.
The hollow would appear from a distance and crawling at top speed toward Ruku to consume him. Ruku would only chuckle at the large hollow that looked like a giant centipede. Ruku would then jump and fly off the limb of the dead tree toward the centipede looking hollow to destroy it. The centipede like hollow would shoot a acidic like fluid from its mouth at Ruku, But he would only block it with his wing which activates his mockery ability. He would counter attack the hollow by beating his wings once brutally toward the hollow as an exact replica of the acidic fluid it possesses would shoot from Ruku's wing feathers landing on the hollows back as it would shriek in agony.
Just before the hollow dies off and fades away, Ruku would consume it's body to become a little stronger. Once the deed was done with the defeated hollow, Ruku would take flight once again and head toward another tree to perch upon it. Awaiting for another hollow to interfere in his territory. Soon enough another hollow would appear in Ruku's sight. This time the hollow was smaller but stronger and very different. It was a lion...
Ruku was to stubborn to stand down so he would attack the powerful lion with his voices of dying hollows screaming and roaring trying to inflict fear into the mammal hollow. The lion would take a swipe at Ruku as Ruku would take it's slash into the mid-torso. Wincing just a bit before landing back on the ground. Ruku would charge at the lions tail and jump just above it taking a side ways soaring so that the edge of his flight feathers would run down the middle of the lion. Cutting it in half as it faded to nothingness. Ruku's scratch would slowly regenerate as he looked back at the lion's dismissal.