Ds1 just bit Ds2 hard on his hand - Ds2 was on my lap at the time and started to cry. I didn't know what Ds1 had done as I was reading something on the computer, then Ds1 told me what he had done and I saw there were marks.
Then I realised that Ds2 had a similar mark on his hand last week too. Obviously Ds1 bit him then as well.
I am very angry about it, but don't know how best to deal with it. He wants my attention probably which I will now go and give him but could use some advice on the best way to make sure this doesn't happen again