I began my weekly pet raid runs this week with just two pets left to get. One of the pets was in Naxx and the other was in AQ.
I started the night in Naxx and headed though the spider quarter first. And Bam! Bone Spider!
I figured being so close I'd be pretty tempted to buy the last pet but I managed to talk myself into trying to get it to drop first. I figured things would look better when the first trash pull didn't drop a red crystal mount. The last three times my death knight has been though that mount has dropped but no pets except the mini mindslayer. In fact the last two weeks I've gotten four of those red mount drops. It's probably a meaningless pattern but it wasn't feeling like one. I thought I might have used up all my luck when I got another Viscidious Globule drop but after killing the twins I found an anubisith idol!
So I finally got the achievement Raiding with Leashes and more importantly Mr. Bigglesworth! Finally done!