The abbreviation DEV stands for submissive.
Since "50 Shades of Grey", at the latest, even many nonBDSM fans that there are practices that require both a submissive and a dominant part. The abbreviation DEV stands within the Scene for the submissive part. Those who during sex (or during the corresponding sex practices) submissive is, submits to the other.
Submissiveness during sex is often expressed through bondage games and the like. Particularly within the BDSM scene, it is the submissive partners are not always about being satisfied. Rather, they enjoy being humiliated. Sex does not always have to be come. Sometimes it also stimulates the parties involved just NOT to have fucked.
Those who like to be submissive themselves but have no partner with whom they can live out their passion usually get their money's worth in relevant sex clubs. Here, like-minded people meet who - ideally - complement each other with regard to their desires.
The possibilities to live out one's weakness for these sex practices are extremely versatile. Some BDSM fans go for physical pain, while others are more interested in the act of humiliation itself. They let themselves be taken out on a leash or can get excited about being insulted.
But by the way, it is a prejudice that especially people who have to make important decisions in private and business life are submissive. Fans of this sex practice can be found in all areas. Those who would like to live out their penchant for being submissive at home will usually find suitable toys in any sex shop.