At first you might not think of addictions as something "freakish" unless it involves porn or a weird sex fetish, but if you hear a first hand account, you may reevaluate that opinion. Issues with drugs and alcohol are usually skirted around in the romance genre, but some authors dare to go there.
I have full respect for J.R. Ward for doing so in book 7 of the awesome BLACK DAGGER BROTHERHOOD series, LOVER ENSHRINED. Her main character, Phury is hooked on a fictional (I think) substance, and is ultimately saved by the power of love. Although this was my least favorite of the series, Phury's struggle tore at my heart. It also made me realize that as with any flawed character, there's a place for redemption for substance abusers in romance novels.
I don't know enough about drugs to yet dare to cover them extensively in one of my novels yet, but one of my heroines is an alcoholic. Writing about her issue brought back memories of how close I came to walking in her shoes during the end of my previous marriage. Another character will fight with her cigarette addiction, a dragon I plan to tackle when I turn 30.
Being that many of my heroes are writers and rock stars, many have dealt with these issues. The most prominent two that come to mind are Stephen King and Dave Mustaine (Lead singer and guitarist of MEGADETH). I've read ON WRITING a kajillion times and I just finished reading MUSTAINE and I'm fascinated at the parallels between the two. Both nearly lost their lives due to substance abuse and both had amazing wives that contributed to their redemption.
If such miracles can happen in real life, then surely they have a place in fiction.