You are a shinigami, and your job is to kill hollows and send souls to Soul Society. You were a great student in Shinigami academy and plus your were strong. But... Not strong enough to defeat an espada.
One day you were sent to the Karakura town, since recently many more Hollows began to appear there, and they cannot always rely on Ichigo.
You walked around Karakura in your Shinigami form, and no one could see you because they dont have enough Reiatsu to be able to see you or any hollow. You kept walking until you heard a loud noise that sounded like a explosion and you immediately ran in this direction where you heard this sound.
When you got there, you saw Ulquiorra and Yammy, and then you started a fight, but got defeated. Ichigo came to save you, Sado and Orihime, but he lost too because he got too emotional. Urahara and Yoruichi came, so Yammy and Ulquiorra had to retreat.
Once they left, Urahara took good care of your wounds and you had to rest in his shop for 5 more days. All these 5 days you helped with the shop and played with Ururu and Jinta, but finally you fully healed and you were supposed to back to Soul Society. Urahara opened senkaimon for you, and you went through it.
Now you were between Soul Society and world of living, but strangely it was too silent. You ignored it and continued walking, but then you stopped when you saw a slim figure Infront of you. It was Ulquiorra... He slowly came up to you with his emotionless face
Ulquiorra: "Shinigami... Come with me to Hueco Mundo." It could sound like an question, but it was an order. Order that you'd never fulfil...
You took out your Zanpakuto, but Ulquiorra used Sonidō and appeared behind you, knocking you out very quickly.
Once you woke up, you slowly opened your eyes, but then they went wide when you remembered what happened, and realised you're in some strange room you've never been before. You sat up and realised you were in bed and you quickly turned your head around and saw Ulquiorra with emotionless face.