[Bilbo] must stab the foul thing, put its eyes out, kill it. [Gollum] meant to kill him. No, not a fair fight. He was invisible now. Gollum had no sword. Gollum had not actually threatened to kill him, or tried to yet. And he was miserable, alone, lost. A sudden understanding, a pity mixed with horror, welled up in Bilbo's heart: a glimpse of endless unmarked days without light or hope of betterment, hard stone, cold fish, sneaking and whispering. All these thoughts passed in a flash of a second. he trembled. And then quite suddenly in another flash, as if lifted by a new strength and resolve, he leaped. (5.119)

[Gollum] was anxious to appear friendly, at any rate for the moment, and until he found out more about the sword and the hobbit, whether he was quite alone really, whether he was good to eat, and whether Gollum was really hungry. Riddles were all he could think of. Asking them, and sometimes guessing them, had been the only game he had every played with other funny creatures sitting in their holes in the long, long ago, before he lost all of his friends and was driven away, alone, and crept down, down, into the dark under the mountains. (5.22)

[Bilbo] knew, of course, that the riddle-game was sacred and of immense antiquity, and even wicked creatures were afraid to cheat when they played at it. But he felt he could not trust this slimy thing [Gollum] to keep any promise at a pinch. (5.68)

Now certainly Bilbo was in what is called a tight place. But you must remember it was not quite so tight for him as it would have been for me or for you. Hobbits are not quite like ordinary people; and after all if their holes are nice cheery places and properly aired, quite different from the tunnels of the goblins, still they are more used to tunneling than we are, and they do not easily lose their sense of direction underground – not when their heads have recovered from being bumped. Also they can move very quietly, and hide easily, and recover wonderfully from falls and bruises, and they have a fund of wisdom and wise sayings that men have mostly never heard of or have forgotten long ago. (5.8)