If he was that nice and loveable and happy then why was he doing Heroin ? - clearly he was a deeply troubled person and he could not of been that happy if he was doing such hard core drugs.
Happy, content people don't use drugs as a prop!!
Doing hard core drugs, doesn't automatically mean you aren't happy or that you are depressed. Bad things happens to good people sometimes. He may well have been deeply troubled, but I don't think you can assume that. He started abusing his body from a very young age, so doing drugs may have just become second nature to him, especially when back in Canada and around old friends who have those bad habits too.