Dave is a lawyer who, in his spare time, is a prospect in The Lost MC. In the mission It's War, he and Billy are hanging out in the Lost MC Clubhouse. Billy spikes his bong hit with mescaline, and Billy describes that he "could be trippin' for days."
Later in the game, Johnny can find Dave outside of Goldberg, Ligner and Shyster office as a random character, business suit clad. When you arrive at Dave's location, he'll tell you that his secretary is blackmailing him and accusing him of sexual harrassment. Supposedly, Dave looked at her breasts which "suppressed" her. She's currently in leagues with an attorney and they're going to bring the case to trial. Dave informs you that his wife isn't a nice person and will ruin his life if she gets wind of these shenanigans. He wants you to go and put some pressure on the secretary's attorney in the hopes of making him cease the case against Dave.
Once in control, go towards the lawyer's location. He'll catch on that he's being pursued and take off. Chase him down and fire some rounds into his car. Eventually, he'll give up and you're told to speak with him. Johnny informs the lawyer that the only good one in his book is a dead one, and the guy will be a really good lawyer if he doesn't give up the case. He'll agree and speeds off, with the mission ending successfully, rewarding Johnny with $500.
- The Lost and Damned
Dave Grossman's Random Encounter