Marauders could refer to:
Relationship with Harry Potter
James Potter: Harry's father
Sirius Black: Harry's godfather
Remus Lupin: Harry's friend and favorite teacher
Peter Pettigrew: Enemy (death Eater)
Early Friendship of the MaraudersTemplate:Character Full Infobox"Four magical mischief makers from Gryffindor who would all go on to play vital roles in the rise and fall of Lord Voldemort." - J.K. Rowling, Pottermore.
James Potter, Sirius Black, Peter Pettigrew, and Remus Lupin became friends during their time at Hogwarts. When James, Sirius, and Peter found out that Remus was a werewolf, they were determined to help him.  Before the invention of the wolfsbane potion, Remus was forced to experience a very painful transformation into a werewolf every full moon. Remus would sometimes be unable to control himself in werewolf form. Upon finding out his secret, James and Sirius created a plan to help their friend. James, Sirius, and Peter became unregistered animagus', giving them the ability to shapeshift into their chosen animal. James became a stag, Sirius a dog, and Peter a rat. Becoming Animagus' also granted the group the ability to explore the castle grounds at night without being caught.
After turning themselves to Animagus', James, Sirius, and Peter created nicknames for themselves. James and Sirius had already started calling Remus 'Moony', a joke meant to tease him about his unwanted werewolf transformations. After becoming Animagus', the group decided they needed nicknames both for them to call each other on and off the map. James took the name Prongs, speaking of his stag antlers. Sirius took Padfoot (after the paws of his dog animagus) and Peter wormtail (his worm-like rat tail). These nicknames stuck with them for the rest of their lives. Later on in both the Harry Potter books and movies, Padfoot and Wormtail are mentioned. Harry, Ron, Hermione, and the Order all call Sirius Padfoot as an undercover name. At that time Sirius Black was on the run after his escape from Azkaban and even mentioning his name could bring dementors and aurors to investigate. Sirius, Remus, and even the Dark Lord himself call Peter Pettigrew Wormtail in the later books and movies. Remus is occasionally mentioned in later books as Moony, but this is rare.
Creation of the Marauders Map
With help from both their Animagus abilities and James' invisibility cloak, the Marauders were able to easily explore the castle. They started mapping all the classes, rooms, and passageways in the castle. They then enchanted the map using the Homonculous Charm, which enchanted the map to track the movement of everyone in the castle. A second charm enchanted the map to repel the curiosity of Severus Snape.
At first look, the Marauders map appears as a blank piece of parchment. To activate, one must tap the map with their wand and say 'I solemnly swear I am up to no good.', a phrase intended to be a joke between the Marauders. The front of the map says 'Messrs Moony, Wormtail, Padfoot and Prongs are proud to present: the marauder's map.'. The possessor then can unfold the parchment, revealing a full map of Hogwarts and all its residents, and even unwanted visitors. To turn the map back into a blank parchment, one must again tap their wand to the map and say 'Mischief Managed.'
Confiscation and Rediscovery of the Marauders Map
Arch-nemesis of the Marauders, Severus Snape was constantly looking for a way to expose the group's troublemaking. Snape eventually tipped off Argus Filch of the map. Filch confiscated the map during the Marauders' last year at Hogwarts and none of them were able to steal it back from Filch, who was very prepared for them to do so. Years later however, Fred and George Weasley found a drawer labeled confiscated in Filch's office. The twins stole the map and used it until their 5th year at Hogwarts, when they then gave it to Harry Potter in his third year, allowing him to use the secret passageways to get to Hogsmeade. At that time, Fred and George, along with Harry, were unaware that the map had once belonged to Harry's father and his friends.
The Marauders' Relationship with Severus Snape
While it isn't much talked about in the books, it can be assumed that most of the grudges held between Severus Snape and the Marauders had to do with Lily Potter, then known as Lily Evans. Severus had grown up in a town called Cokeworth, along with Lily Evans and her muggle sister Petunia. Lily had met Severus when they were 9, and Severus fell in love with her. They became close friends, and Severus taught her what he knew about the magical world until they both started attending Hogwarts. in 1971, Lily and Severus along with the Marauders started going to Hogwarts. Snape was put in Slytherin and Lily and the Marauders in Gryffindor. James had an instant crush on Lily, and that along with their rival houses made Severus and instant enemy of James and Sirius. Snape fell in with the Slytherin pureblood bullies, straining and eventually ending his friendship with Lily. In their fifth year, Severus became a death eater in an attempt to win back Lily's affection. Throughout their years at Hogwarts, The Marauders, led by James, continuously bullied Severus even after Lily begged James to stop. This rightfully made Severus Snape bitter against James Potter and his friends. Severus was also in love with Lily while she was dating James, so him being bullied by them on top of jealousy gave Severus motive to constantly try to get the group in trouble for their constant mischief being managed.
Adult Friendship of The Marauders and The Death of James and Lily Potter
NOTE: THE FOLLOWING PARAGRAPH INCLUDES SPOILERS AS TO THE EVENTS OF HARRY POTTER AND THE ORDER OF THE PHOENIX, PRISONER OF AZKABAN, AND DEATHLY HALLOWS.
The Marauders graduated from Hogwarts in the spring of 1978. James Potter married Lily Evans sometime between the summer* and fall of 1978, and Sirius was their best man. In the fall of 1989, Severus Snape (who at the time was a spy, on Voldemort, for Dumbledore) informed Albus Dumbledore that Voldemort had heard of a prophecy from Sybill Trelawney that read "The one with the power to vanquish the Dark Lord approaches... born to those who have thrice defied him, born as the seventh month dies... and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not... and either must die at the hand of the other for neither can live while the other survives... the one with the power to vanquish the Dark Lord will be born as the seventh month dies....". Snape knew that Lily Potter was pregnant and that the baby was due in July, and was probably forced to reveal this information to Voldemort. Snape then begged Dumbledore to protect Lily, who he was still in love with. James and Lily went into hiding using the Fidelus Charm, a spell that hides a secret in a designated person. The Potter's choose Sirius, James' best friend, as their secret keeper. On July 31st, 1980, Lily Potter had their first and only son, Harry Potter. During October of 1981, Sirius told Peter Pettigrew where the Potter's were hiding. James and Sirius trusted Peter, who had been their good friend since they were 11 years of age. Peter had become a follower of Voldemort. Wanting to please the Dark Lord, Peter gave away the Potter's secret to Voldemort, revealing their hiding place in their home. On October 31st, 1980, James and Lily Potter were killed by Lord Voldemort.
After Sirius found out about what Peter had done, he begged Rebeus Hagrid to let him take Harry, as Sirius was Harry's godfather. Hagrid declined as Dumbledore had already requested Hagrid give the baby to Dumbledore for him to take to live with Harry's aunt and uncle, Lily's muggle sister Petunia and her husband Dudley. Sirius then gave his motorcycle to Hagrid and ran to find Peter Pettigrew. Peter and Sirius fought, and it appeared to the muggles around that Sirius was the bad wizard as he was the one who approached Peter. Peter faked his own death in an explosion, cutting his finger off as he turned into a rat and scurried away. Sirius went to Azkaban for 12 years, but escaped in 1993 after seeing a photo of "Scabbers" with Harry and Ron in a daily prophet article and realizing it was his traitorous former friend Peter. In Harry Potter and the Prisoner of Azkaban, Harry, Ron, and Hermione meet Sirius in the Shrieking Shack (unintentionally), along with Remus who was their dark arts professor at the time. Sirius and Remus greet each other as old friends and turn scabbers back into Peter and attempt to kill him, but he escapes and runs back to Lord Voldemort.
Remus and Sirius stayed friends until Sirius is killed two years later in Harry Potter and the Order of the Phoenix. Voldemort tricks Harry into thinking he has kidnapped Sirius and lured the Trio along with Neville Longbottom and Luna Lovegood to the Ministry of Magic. The Order then followed with Sirius to save Harry and his friends, but Sirius' death eater cousin Bellatrix Lestrange kills Sirius.
In the spring of 1998, Peter Pettigrew is killed by Voldemort in the Malfoy Manor after Peter hesitates to strangle Harry. Harry, Hermione, Ron, and Luna had been held captive in the Malfoy Manor after being picked up by snatchers in the woods in Harry Potter and the Deathly Hallows.
On May 2nd, 1998, Remus and his wife Nymphadora Tonks are both killed during the Battle of Hogwarts. Tonks was murdered by Bellatrix Lestrange, and Remus by Antonin Dolohov. Remus was the last Marauder to die.
*Please note that this is time in the Northern Hemisphere, as the Harry Potter books took place in Europe.
 Pottermore-Writing by J.K. Rowling: "The Marauder's Map"
 Pottermore by J.K. Rowling
↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Pottermore - Writing by J.K. Rowling: "The Potter Family
↑ Pottermore - Writing by J.K. Rowling: "The Magical Congress of the United States of America (MACUSA)"