Monroe first meet when Nick thinks he is guilty of kidnapping a little girl in a red sweatshirt. Nick is just coming into his powers and doesn't know what's going on when he see's Monroe's true face. Monroe proves his innocence by helping Nick find the real kidnapper and saving the little girl.

Monroe is a Wider Blutbad who from then on aids Nick with his cases. He is also a good friend of Nick's, even though he has some issues with Grimms since a Grimm killed his grandfather (although he acknowledges that the ancestor deserved it for butchering a village). Monroe at first did not know that there were any more Grimms left until he meets Nick. Monroe is attacked by the Reapers for assisting Nick in his cases. Nick tells Monroe that he won't ask for his help any more, but Monroe resolves to still help Nick, stating that he enjoys helping Nick disrupt the 'status quo' despite his occasional dissatisfaction with the demands Nick places on him.

Monroe is knowledgeable about the supernatural creatures that Nick goes up against, serving as Nick's direct source of insight and information into the supernatural community whenever the second-hand knowledge that Nick acquires from his ancestors' books is inadequate, as well as assisting Nick when cases require Nick to rely on someone who knows about the threats he faces. He also helps Nick make contact with creatures that would avoid Nick due to his status as a Grimm.

When Monroe's friend was injured and suffering from the side effects of an experimental drug, he takes his friend's jacket and make the search dogs chase him. While being chased in the forest, he is surrounded by the search dogs and transforms into his Blutbad form to scare them off, but runs into Hank when he heads back to his house. Because he "allowed" his changed form to be seen by normal beings, Hank was able to see it before he runs off. In the season finale, Nick brings Juliette over to Monroe's place so that he can change in front of her, to prove his Grimm heritage, but before Monroe could "allow" himself to be seen by her, Juliette collapses from the scratch made by Adalind's cat. Monroe is now exploring a relationship with Rosalee, although they are taking their time due to their pre-existing friendship. While running the Spice Shop, Monroe comes into contact with Sean Renard who is complaining of obsessive behavior. Monroe says he can make the compulsions go away, but he needs both Sean and the person he is obsessed with together. He discovers that the obsession Sean has been fighting is for Juliette, which puts him in a very difficult and awkward situation. He and Rosalee help Juliette and Captain Renard break the bond between them.