In all the little hobbit's honesty, Bilbo Baggins of Bag End did not think he would live as long as he did. He surprised all who lived in the Shire, most thinking that he should be six feet under where they stood-possibly so that they could snoop for the supposed 'treasures of Erebor' in the pantry. Or his cousin would steal his spoons again.
It was only when he returned to Rivendale, the first Elven kingdom he came across, that Bilbo was started to feel the Hours catch up to him. He began to walk slower, more because he was out of breath, rather than to drink in the beauty of the white halls and calm vitality of nature creeping in where it could. It certainly surprised him, when Bilbo found his nephew, Frodo, stumble into Elrond's home with-
Not the Ring.
When he saw the small trinket hanging around Frodo's neck, Bilbo felt an urge: One that he had fought for so long. One that drove him to mindlessly destroy another life. Because it was his.
He tried to lay his hand on his own nephew. His own flesh and blood.
What would Thorin think of this? The late King would never commit such a crime to his nephews, or any of his brethren...Except for those days...when the King was mad with the cursed Dragon Sickness. The plague on the mind, corruption because of the gold and wealth that beckoned Smaug to destroy Dale and take Erebor under his god-sized wing in the first place.
How could Bilbo allow the Ring to corrupt him so? Was this how Thorin felt when I offered the Arkenstone to Bard and King Thranduil? The urge to do anything to get it back? But Bilbo held back at the last minute, only just enough so that Frodo saw the darkened creature Bilbo almost became. And Frodo forgave him, realizing the danger of having the cursed Ring in his possession and the importance of the mission of destroying it in Mount Doom.
"Forgive me, my boy..."