Ray can be a very bitter character at times. He's not one to sit and cry but will mope around now and again. He's a sensitive soul but keeps his angst bottled up. Smoking helps to reduce the pain.
To any of you observant enough, Ray has quite a few parts of my own personality and certainly my ex's. My ex was a bitter man due to past experiences but had a good heart deep down. I'm a bitter person, humanity doesn't stop failing me. My ex still treated me wrongly especially towards the end, but the time we had was amazing. My ex was also a smoker and smoked more when anxious or depressed. What can I say? I like broken people. House remains my favourite character of all time. I wanted to create Ray as a misunderstood being stuck in situations not his fault.
He does have a heart deep down, just have to find it first.