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O Collector também conhecido como Taneleer Tivan pode ser visto em MCU e ele é realmente um ser muito mais poderoso originalmente em quadrinhos do que retratado no MCU
"I present to you, Taneleer Tivan, the Collector!" ―Carina (in Guardians of the Galaxy)
MCU wikia explica sobre o colecionador da seguinte forma,
Taneleer Tivan, also known as the Collector, is the keeper of the largest collection of interstellar fauna, relics and species in the galaxy, operating from the Knowhere port installation. Through his dealings with Asgardians and the Guardians of the Galaxy, he was in possession of one of the Infinity Stones and was nearly able to obtain a second stone. However, this caused Thanos to attack his museum seeking the Aether.
explica ainda como a Tivan conseguiu a pedra em primeiro lugar,
In 2013, two Asgardians, Sif and Volstagg, arrived at Tivan's museum, bringing with them the Infinity Stone known as the Aether, which had been recovered by Thor after his battle against Malekith on Earth. They gave it to him believing that it would be safe from other parties. When Tivan asked why they did not keep the Aether in their own vault on Asgard, they explained that they thought it would not be wise to keep it on Asgard since another stone, the Tesseract, was already on there; a notion that Tivan agreed with. As Sif and Volstagg left the Aether in Tivan's care, Tivan remarked to his assistant, Carina, that they now had one of the Infinity Stones in their possession, and only needed the remaining five, hinting that Tivan was already seeking the Infinity Stones. Tivan learned the location Power Stone, which was contained inside the Orb and begun working out a plan to obtain it for himself.
De uma resposta para uma pergunta semelhante na SciFi SE
MCU version of Tivan portrays him as just an eccentric collector so far, the comics version has a personal mission of collecting artifacts and subjects and keeping them safe so that the Universe could be repopulated. Not only does Tivan have a personal mission to keep all of these artifacts safe, he also has ten heavily guarded museum worlds, as well as a ship that remains in hyperspace almost all of the time to avoid being detected. Additionally, he has "temporal assimilator" which can be used for limited time-travel.
Houve uma conversa entre Thor e Senhor das Estrelas na Guerra do Infinito dos Vingadores,
Star-Lord: "If it's with the Collector, then it's not safe. Only an idiot would give that man a stone."
Thor: "Or a genius."
POV de Reddit
In MCU The Collector was a known buffoon - despite his reputable collection of things, he was a joke across the galaxy. But then the Asgardians realized that the one place nobody ever thought they'd keep the reality stone was with a well-known doofus.
It's essentially the galactic version of hiding something in plain sight, like stealing the Mona Lisa and hanging it a small town community art museum, nobody would ever think something so valuable would be in such a non-descript place with such an idiot guarding it that they wouldn't even bother to look there in the first place.
Eu encontrei outro POV no reddit,
Personally, I felt the most important reason was that The Collection had no intention of using it. Odin/Loki didn't trust having two infinity stones on Asgard, so he probably wouldn't trust the Nova Corp with it either, nor the Avengers, since Earth had two already.
So, Collector can be choosen for
Has the ability to protect a stone,
Would be willing to have a stone, despite it potentially putting a bullseye on them.
- Can be trusted not to abuse it.
The Collector wants it for its rarity and collectability, not the things he could do with it. He wasn't going to go try take over the galaxy with reality warping power. So, he was a good choice. The only question was his ability to safeguard it. Assuming no-one would find out he'd been entrusted with it, and that the Collector had probably collected a number of defence systems to protect his collection, he was probably a decent enough choice.