In Lord of the Rings, it may seem peculiar that the One Ring does not affect Bilbo in the same way it affects Frodo. Bilbo Baggins is Frodo's uncle, and after taking him in at Bag End, he names Frodo his heir. Little does Frodo know, Bilbo's inheritance comes with much more than just a Hobbit hole. It comes with the One Ring itself, the most powerful object ever created in Tolkien's universe.
In The Hobbit, Bilbo finds this incredibly powerful ring and carries it with him for many years. However, the corrupting, maddening effect it has on Frodo does not seem to manifest as powerfully in Bilbo. Firstly, it should be noted that when JRR Tolkien wrote The Hobbit, he had not yet fully conceived the power and purpose of the Ring, which explains the discrepancy from a writing standpoint. Interestingly, there is also an in-universe explanation for the difference in the One Ring's impact on Bilbo and Frodo, respectively.
Bilbo's Comion Protected Him From The Ring's Corruption
One thing that protects Bilbo from the corruption of the Ring is his comion. After finding the One Ring in the goblin tunnels under Misty Mountain, Bilbo escapes by using the Ring to turn invisible. He sneaks past Gollum and the goblins guarding the tunnels, but he has a chance to kill Gollum on his way out. Luckily, Bilbo's comion causes him to show mercy. The importance of that moment is revealed in one of Gandalf's wisest quotes when he tells Frodo that Bilbo’s pity and comion in acquiring the Ring help protect him from its corrupting power:
“Pity? It was Pity that stayed his hand. Pity, and Mercy: not to strike without need. And he has been well rewarded, Frodo. Be sure that he took so little hurt from the evil, and escaped in the end, because he began his ownership of the Ring so. With Pity.”
It's helpful to contrast the way Bilbo acquires the Ring with the way Gollum does. Bilbo begins his ownership of the Ring with an act of mercy, whereas Gollum acquires the Ring by murdering a friend. This act of selfish cruelty causes Gollum, then known as Smeagol, to immediately fall victim to the Ring's corrupting influence. As a result, the Ring poisons Smeagol for the next five centuries, eventually turning him into the creature known as Gollum. It's clear when comparing Gollum and Bilbo that Bilbo's comion protects him from the Ring; however, Frodo is comionate as well, so there must be another factor at play.
The Ring's Powers Were Stronger On Frodo Because Of Sauron
The other essential factor that helps for the Ring's stronger influence on Frodo is the relative strength of Sauron when Frodo possesses the Ring compared to when Bilbo has it. Sauron is nearing a return to full strength during Frodo's journey, which seems to make the Ring more potent. The Ring also seems to have a greater influence on Frodo the closer he gets to Mordor. Part of that increasing influence is likely related to the amount of time Frodo spends with the Ring, but Sauron's strength and proximity are still massively important factors.
Part of the reason Sauron's proximity to the Ring makes its influence stronger is that the Ring desperately wants to be reunited with its master. The Ring can sense how near it is to Sauron, and as it draws closer, it begins working harder to corrupt Frodo and find a way to return to Sauron. Frodo is the perfect person to destroy the One Ring, but it ends up becoming so powerful as it nears Mount Doom that Frodo can't make himself do it. If not for Gollum biting the Ring off Frodo's finger and falling into the fires of Mount Doom, the Ring's influence may have won out.
How The Ring Still Affected Bilbo (Just Not As Severely)
The One Ring may affect Frodo more than Bilbo, but it still corrupts Bilbo to a certain extent. The Ring's influence on Bilbo is clear when Gandalf has to force him to leave it behind in The Fellowship of the Ring. Bilbo has clearly grown attached to the Ring after all the years he has been in possession of it. At times, the Ring even seems to cause Bilbo to do things without realizing he's done them. For example, when Bilbo thinks he has placed the Ring in an envelope on the mantle for Frodo, he realizes he still has the Ring in his pocket.
He then struggles to let the ring fall from his hand into the envelope. After releasing the Ring, Bilbo immediately seems more chipper and light-hearted. That immediate mood swing shows how the Ring casts an emotional pall over anyone who holds it. Bilbo might be the best hobbit in The Lord of the Rings, but the Ring influences even him. Luckily for Middle Earth, Bilbo is able to relinquish the Ring, despite its influence over him.
