There is no way Dean is scared of Colby. That is in no way obvious and without trying to sound nasty, its quite frankly a ridiculous assumption. Plus Colby DID have a lot on his plate due to Bella's constantly running off, skiving school. Yes that was due to Ross but still... Plus Chelsea has just left him, regardless of whether you agree with her leaving him or not, he's still lost his wife, yes through his own actions but still..... Plus Willow wasnt really across ALL of Deans actions either now was she? She knew off Karen because she brought her to Dean but nothing else. And he IS concerned for his best mate and he's allowed to be a bit wary of what he's done when out of it. I think he hasnt showed guilt because he hasnt allowed himself too. But at times he has such as when Willow confronted him when he found out she knew, she asked him if he was okay and he said he had to be for Bella's sake. Plus when he got his gun back last week, he was clearly uncomfortable. We've seen glimpses of guilt. I saw no moral high ground either over his drug taking, just concern.