Bec, I have read a book that had a "never say no, never tell off, praise always" thing in - didn't buy it though. Children need to hear "no!". This lad does seem to be searching for the "no" with the behaviour you describe - I tend to tell DS that "We/Mummy don't like scratching, we like cuddles. Cuddles! Oh, thank you Liebling, Mummy enjoyed that cuddle." or something like that. That's not a no, but maybe something you could try if this lad gets agressive again.