Ichigo Kurosaki: [after seeing Sora's face beneath the Hollow's mask] I just don't get it. Why did Orihime's brother attack us?
Rukia Kuchiki: Not us; just *you*. Judging from the last Hollow you killed, I would guess there's a more powerful Hollow behind this that wants to consume your spirit energy. It probably has several Hollows under it's control. It knows where you are now and is sending other Hollows here to carry out it's orders. That would explain why Orihime's brother has come to attack you.
[rushes forward & grabs her shirt; anger in his voice]
Ichigo Kurosaki: And you expect me to kill him now? There's no way I can to do that...
Rukia Kuchiki: [cuts him off as she pushes him away] You have too do it! You haven't got a choice. If you don't kill him he'll wonder around forever.
[pause]
Rukia Kuchiki: And he'll keep coming after you again and again, until he gets your soul.
[suddenly thinks of something]
Rukia Kuchiki: Wait, you aren't the only one in danger!
Ichigo Kurosaki: [voice strained] Who else would he want?
Rukia Kuchiki: Orihime. His sister!