I'm the someone!
It was a long and grueling process to defeat it, thanks to the 72 million health, and it being a MoP level boss (meaning it's basically lvl 93, so a lot of my attacks kept missing).
If you get too close, it jumps on you and you're basically doomed - it fears you, deals massive damage and you're even effected with a 100% healing reduction debuff. Not pretty!. Luckily, it doesn't attack Hunter pets, so I had my pet tank it while I dpsed away at max range. Took a long, long time, would have taken even longer if a friendly Hunter didn't come to help me. We eventually killed it, and were happy to see the Pet drop.
We weren't able to roll on it, I looted the Rabbit and the pet instantly went into my bags (had auto loot on). It was just like looting a grey/white item. I don't think it dropped more than one pet, because it seemed to despawn fairly quickly.
Will be interesting to see exactly how it turns out on live, perhaps the Holy Hand Grenade
that was data mined has something to do with it?
As for the pet itself, it's currently a copy-paste of the Snowshoe Rabbit, with a couple of differences. It has the buff "Vicious Streak" (more Holy Grail references!), and a blood like effect dripping from it's mouth, similar to the look of the Savagery enchant. It's currently tagged as a Placeholder, so we should see a new look soon!
Not Pink, it's a trick of the light!