Biter

Micah has turned into a biter.
A mean biter. A biter who bites with the intention of hurting.
I saw him do it for the first time less than a week ago.  Grey had taken a toy from him, and then turned away so that Micah was facing his brother's back, which was hunched over something he WANTED.
With sudden ferocity, which I had never seen before, he lunged at his brother. Micah's arms wrapped all the way around Grey, pinning Grey's arms at his side and squeezing as hard as he could, and Micah's head slammed into Grey's neck/back, where he clamped down with his three sharp little teeth.
I was horrified, to say the least.
But also, I laughed a little. Where had he learned that? He looked completely insane. 
Grey started crying, so I comforted him and shook my finger at Micah, and kind of didn't think much of it.
Until a day later, when Travis yelled "Holy cow! Micah just totally attacked Grey!" and then on Tuesday, when we were at a friend's house and an older boy knocked Micah down at (on accident) and Micah LUNGED at him, with this crazy maniacal look in his eyes and his teeth sharped for the kill.
But it isn't just biting. It's head-butting, squeezing, pushing, and hurting.
He wants to hurt the person who hurt him and/or took his toys.
It happened once or twice on Wednesday and then several times on Thursday. It's really hard and I don't know how to handle it, and here's why:
Grey starts crying, so my first and immediate need is to scoop Grey up and snuggle him and help him try to feel better.
That, however, leaves Grey's toy unguarded - which means that whatever Micah was fighting for is now free for the taking. If I wait and come back to scold Micah and put him in "time out" (more on this in a second) a few minutes later, then I worry that he doesn't know what he's in trouble for. He's not in trouble for wanting that toy. He's not in trouble for taking the toy off the ground. He is in trouble for intentionally hurting his brother, but how do I make him understand that?
If I try to scold Micah while holding Grey, then Grey becomes even more upset, and I'm worried that he thinks that I'm angry with him.
Gah! TWINS. Did I mention that they're only ten months old? How do you teach a ten-month old right and wrong?
Oh, and "time out:" Travis said that Micah needs to learn that doing bad things makes him feel sad, so I need to make him sad when he does something wrong, by taking him away from the fun. So when Grey isn't hysterical, or there's someone else around to comfort Grey, I try to take Micah into another room for a minute or two while I explain what he did wrong.
Again, though... explain? Really? To my not-even-one year old?
I usually say "Micah, no! We do not hurt our brother. We love Grey, and even if we're mad we can't try to hurt him. I'm sorry that Grey took that toy (or is in your way, or is being held by mom when you want mom), but we need to always be nice to other people."

Yikes, that seems weird. I shouldn't say "we," right? But "you" sounds so accusatory, and I mean... I love Grey and try not to hurt him, too.  Anyway.

I did see something encouraging yesterday though. Micah was playing with this little baby xylophone and Grey scooted in next to him to play, and slowly Micah started to get edged out. And he was mad.
Grey was sitting, and Micah stood up, teeth bared and fingers out -about to attack him- and then suddenly stopped.  He turned and looked at me, with this face like "What now?"
Maybe it wasn't really his thought-process, but to me it seemed like he remembered (just in time) that I told him not to hurt his brother, so he turned to see what I wanted him to do instead.
I smiled as big as I could, and told him that I loved him, and he was such a good brother for sharing and I was so, so glad that he had decided not to hurt his brother, and motioned for him to come over by me and look at the other toys.  He slowly walked over to his pile of books, and picked up a picture book of animals and carried it to me, and then sat down in my lap.

Sigh. Oh my goodness, it was so sweet.
And I was so proud of him.
I really do think that he was deciding to make a good choice.
We read the book three times through, and he didn't make a peep (although he usually makes all kinds of noise when I read stories). Instead he concentrated on his hands; I made baby signs for the few animals I know signs for (like horse and frog and kitty) and he tried to copy me.
My favorite was frog. He was trying so hard, and just kept flicking the page and then smiling up at me for approval.
Such a good boy. I love him so.

But also, I don't think that we've seen the last of biting.  Any advice on teaching your baby how to be good?