History Series / Grimm

* HumanMomNonhumanDad: {{Inverted}} with the Naiads. The men are all infertile so the women have to mate with human men. In the olden days, males resented the fact that they have to raise the children of other men so much that a tradition sprung up of killing the human fathers. Modern naiads don't necessarily engage in the practice, but it does happen.

** Averted with Max, a one-off character "The Show Must Go On" suffering from uncontrollable voges. When two women start trying to undress him against his wishes, the show clearly shows their behaviour as wrong and plays out the same way it would had the genders been reversed, and they both end up dead as a result (though Max still seems to feel guilty for it..but so would anyone).

* [[WhyDidItHaveToBeSnakes Why Did It have to be Rats?]]: In "Danse Macabre." Hank reveals he's terrified of Rats. Brought up again later when he's introduced to a Reignigen (a rat like wesen),

* MindOverMatter: [[spoiler:Adalind's baby]] is rapidly showing to be proficient in this, even forcing a Verrat to commit a PsychicAssistedSuicide. Presumably, all [[WitchSpecies Hexenbiests]] and Zauberbiests have this to a limited extent, but [[spoiler:the baby]] turns this UpToEleven having been supercharged by [[spoiler:the ritual that returned Adalind's powers]].

* [[NeverMessWithGranny Never Mess with Auntie]]: Aunt Marie really puts the English on the trope given she's ''dying of a terminal illness'' and still takes on Hulda with only a knife (a knife concealed in the handle of [[SwordCane her cane]], that is) and her BaldOfAwesome. We find out later she was a BadassBookworm, having been a librarian by trade. She also stares down Monroe while she's clinging to life in a hospital bed. Considering we see Monroe rip off a man's arm a few scenes later, that took no small amount of guts.

* StuffedIntoTheFridge: Juliet's an easy target for those looking to hurt the Grimm but not having the chops to attack him personally. [[SubvertedTrope Unfortunately for them]], Juliette is a bonafide DamselOutOfDistress and is consistently able to fight back against anyone who gets up in her proverbial grill, be it a Hexenbiest or a Manticore.

* FairyTales: Each episode is at least partially based off of one (if not a WholePlotReference). Those that aren't are based off general folklore or creepy stories and factoids from around the world.

** Monroe is pretty confident that Santa Claus is both real and not human; being a Gefrierengeber ([[BilingualBonus German]] for "freeze giver", would make him capable of living "up there". Nick doesn't elaborate for the viewers but seems to take the suggestion seriously.

* HeroOfAnotherStory: One a Nick's ancestors, a Grimm who ran with a team not unlike Nick's and operated out of London in the early 1900's.

* RealityEnsues:
** Back an animal or a person into a corner and push them beyond endurance and they will become violent no matter how timid they may be. Demonstrated with the supposedly cowardly Mouse in 1x09.
** Wu eventually connects "criminology student" Theresa Rubel with the suspect in a dual homicide case. Nick and Hank's continual evasions make him extremely uncomfortable and prompt him to take the matter to Renard behind their backs.

* InstantBirthJustAddWater: The birth scene in "Endangered" is extremely quick, and there is a minimum amount of gore, but this might be Justified by the fact its technically a different species, and their biology is stated to be different on some accounts.
** Jocelyn's labor is implied to have started much earlier in the day while her and her husband are still in their vehicle. She even tells him that she needs to rest or she'll have the baby right there. Then her husband leaves her in the abandoned cabin and the Grimm gang (and the viewer) don't see her until well after dark. She could have been having continuous contractions which stepped up in intensity at that moment.

** The keys with the map that the Royals are looking for are promptly forgotten in later seasons, [[spoiler:until halfway through Season 5, when Nick unexpectedly comes into possession of 3 additional keys. Together with the 2 they already had (which have been hidden in the spice shop since the trailer burned) they have enough of the map to go looking for the treasure. When the treasure is finally recovered in "Into the Schwarzwald", it's revealed to be a ordinary-looking stick with the ability to heal. As it turns out, only 5 of the keys were required (Nick unsealed the box with his blood), so it's possible that the location of the last two keys will never be revealed.]]
** And then there are the Coins of Zakynthos. [[spoiler:Nick's mother Kelly takes custody of the coins and plans to destroy them at the only place they can be destroyed, the island upon which they were made. After quite some time Kelly e-mails Juliette saying that the coins are hidden for safekeeping. A Season or so after that Kelly is killed and the coins are presumably forgotten]].
** Black Claw is pushed into the background after [[spoiler:Renard ends his association with them. Hell, the entire organization is KilledOffscreen by Truble]] The shortened final season probably had something to do with this.

** When she regains her Hexenbieste powers (the second time), Adalind worries aloud that her old amoral attitude will come back with them, and shortly afterwards is relucant to show her GameFace to an old acquaintance. This is never brought up again, and apparently her mentality doesn't change at all even though Juliette became borderline sociopathic after she was transformed into an Hexenbieste.
* ActingUnnatural: After realizing Juliette's friend Alicia, who is staying with them while hiding from her abusive husband, is a fuchsbau, Juliette and Nick both decide to say nothing and "act natural" to avoid frightening her with the fact that Nick is a Grimm. Despite being perfectly capable of feigning normalcy on their own, their idea of acting normal together is to stop what they are doing, plaster on benign smiles, and stare silently at Alicia.

** Juliette [[spoiler:was able to use her new hexenbiest mojo to stab a manticore hitman to death with ''his own tail''.]]

** When she regains her Hexenbieste powers (the second time), Adalind worries aloud that her old amoral attitude will come back with them, and shortly afterwards is relucant to show her GameFace to an old acquaintance. This is never brought up again, and apparently her mentality doesn't change at all.

** After regaining her Hexenbieste powers, Adalinda worries that her old amoral attitude will come back with them. This is never brought up again, and apparently nothing of the sort happens.

* InstantBirthJustAddWater: The birth scene in “Endangered” is extremely quick, and there is a minimum amount of gore, but this might be Justified by the fact its technically a different species, and their biology is stated to be different on some accounts.

* NotSoDifferent: Orson confronting Nick when the latter knows that he's of Bauerschwein origin. The former believes that they should work together as police officers and not in the Grimm - Monster hunting view. Nick doesn't agree, [[spoiler:considering Orson's involvement in Hap's death]].

** The Bauerschwein are the basis of the Literature/ThreeLittlePigs. Needless to say, Blutbaden and Bauerschwein typically aren't on friendly terms.