Thank you everyone. I'm really discouraged and frustrated, and I know the cats are both frustrated right now too. I'm keeping Ember's claws very blunt and letting Kyubey's grow for now. I am going to call the shelter Monday if I haven't heard from them and see if they can please please make room for him.

The person I spoke to about his behavior pretty much just suggested that I play with him more and get him some interactive toys that he can play with while we're out of the house. I was rather frustrated by the advice because I already play with him a LOT, and I have bought both a battery-powered table-laser thingy and a ...er...I forget what it's called...a fabric circle with an electronic 'mouse' that whirls around for him to chase. We also have half a dozen or so of those ball-track round toys scattered throughout the house, which I hear him playing with regularly. I set aside 20-30 minutes to play with him in the morning and the evening, and I toss toys for him whenever I get a chance throughout the day. During his morning and evening play sessions, we go until he is panting and laying down every time he catches the toy. I work part-time so I'm home to play fetch with him a lot too!

When it was suggested I play with him MORE, I took the next few days and made sure he got at least two hours of active play. He was exhausted! Still, twenty minutes after I turned out the lights to go to bed he was all over Kyubey, and he started again at dawn. >.< My friend was over last night and we decided that Ember is the feline equivalent of a Jack Russell terrier...energetic, wickedly smart, with a shot-out-of-a-cannon play style.