Aragog was originally brought as an egg in a distant land and came to Great Britain in the pocket of a traveller. Somehow, the egg came into possession of Rubeus Hagrid, who at the time was a student at Hogwarts School of Witchcraft and Wizardry.
Hagrid raised Aragog from an egg as a Hogwarts student, keeping him inside a cupboard. In his third year at Hogwarts, Hagrid was caught talking to Aragog in the dungeons by Tom Riddle, who alleged that Aragog was the "Monster of Slytherin", and that Hagrid had opened the Chamber of Secrets.
In Harry Potter and the Chamber of Secrets, Aragog tells Harry (Daniel Radcliffe) he came to Hogwarts from a distant land, “in the pocket of a traveler.” Newt is famous for keeping magical creatures in his pockets, his bowtruckle Pickett being a trusty sidekick by Fantastic Beasts 3.
Hagrid mentions in the Harry Potter and the Chamber of Secrets that Aragog was given to him by a traveller. There is a theory that says that Aragog was given to him by Newt Scamender. According to the theory, Newt visits Hogwarts and in the process meets Hagrid and gives him Aragog after seeing his love for animals.
Newt Scamander Gave Aragog to Hagrid - Harry Potter Theory
Why did Hagrid send them to Aragog?
Hagrid told Harry Potter and Ronald Weasley to follow the spiders to find out the truth. Aragog was sleeping in the center of their hollow when his children woke him up to give him Harry, Ron and Fang.
You'd be great friends with Aragog. When a young Voldemort made Aragog a scapegoat for the Basilisk's attacks on Hogwarts' students, Hagrid – a student at the time – helped the overgrown spider to find sanctuary deep within the Forbidden Forest.
Aragog had a close friendship with his former owner, Hagrid. He admitted that it would have been his instinct to try to attack humans, but he restrained himself out of respect and gratitude for Hagrid, and unlike the Basilisk herself, he never personally harmed a human in his life.
So it's altogether possible that a younger Hagrid met a middle-aged Scamander at Hogwarts in the '40s. There's another connection (besides caring for misunderstood beasts of the world) between the two. Hagrid and Scamander were both expelled from Hogwarts, only to return as professors later.
He knew that this was the Basilisk, so he would have been scared that it would find him, and being ancient enemies, the Basilisk would have dealt him a merciless death.
Mosag was only mentioned passively in Harry Potter and the Chamber of Secrets, and is not mentioned in the film version. It is unknown if Mosag fought in the Battle of Hogwarts. Because she never actually appears and is only briefly mentioned once, it is possible that she died sometime before Aragog.
At that point Hagrid was expelled, but he managed to release Aragog into the forest, where the Acromantula spent the rest of his life. Hagrid later found a mate for Aragog named Mosag, and they had many offspring; the entire colony remained deep in the forest.
At the beginning of the Battle of Hogwarts, the Death Eaters invaded the home of the Acromantula and drove them to attack the school. When the spiders attacked, Hagrid ran forwards to protect them. Acromantula are horribly strong, so it is likely that they captured him and took him to Lord Voldemort.
Hagrid knew who Voldemort was before Voldemort appeared at the political scene of the magical world. He just refuses to use either of his names. And when he gave Harry the name, he gave him the name, Harry had to know. Hagrid very well knew, Voldemort was Tom Riddle.
Even with Dumbledore backing Hagrid, Minister for Magic Cornelius Fudge insisted on taking Hagrid anyway. So on the same night Dumbledore was asked to step down as Headmaster by the school governors, Hagrid was escorted to Azkaban.
True to their name, Acromantulas are massive arachnids who tend to spin their expansive webs high in tree tops. Despite the names bearing a phonetic similarity to tarantulas, they appear more like Wolf Spiders and are, in all depictions, araneomorphae.
As depicted in Harry Potter and the Prisoner of Azkaban, Newt Scamander visits Hogwarts in 1993 or 1994 for some unknown reason, thus appearing on the Marauder's Map. Newt writes A Children's Anthology of Monsters, an edition for younger readers. As of 2017, Newt Scamander is still "alive and well".
No. You do realize that Hagrid is his surname and that his first name is Rubeus, right? If Newt Scamander were his father, then his name would be Rubeus Scamander. Not to mention that Hagrid stated that his father died while he was still a student, while Newt was still alive in the 1990's.
When Newt and his best friend, Leta Lestrange, were 16, Leta's illegal experiment with a magical beast called a Jarvey endangered the life of a fellow student. However, Newt took the blame for the incident, resulting in him getting expelled from Hogwarts.
That same year, Aragog contracted an unknown illness over the summer, and despite Hagrid's attempts to heal and comfort Aragog by feeding him giant grubs, he eventually died on 20 April, 1997.
Aragog is described as a massive, dark, hairy brown/black Acromantula with the ability to communicate with humans. His size dwarfed that of his offspring and he possessed eight eyes that were milky white and totally blind, possibly due to his advanced age.
He is closely associated with the Order of the Phoenix, and has explicitly denied the anti-Muggle/Muggle-born ideology of the Death Eaters. There is quite literally NO plausible way Hagrid could be or ever have been a Death Eater.
He probably got to know Harry was a Horcrux when he saw the Scar on Harry's forehead, but maybe he wasn't sure. Then, when Harry came to Hogwarts and Dumbledore got to know he can speak Parseltongue his thought of him being a Horcrux got stronger.
He was eventually forced to accept that his father was the Muggle parent, and that his mother was the magical one. It was around this time that Riddle gave himself the alias "Lord Voldemort", to spare himself of the reminder of his "filthy Muggle father".
