The Fellowship of the Ring Book 1, Chapter 10
Strider comes to Frodo's room and tells him that he has advice for them. He tells them that they must take him with them. Frodo says that he would have to learn a lot more about him before he is willing to take him along. Strider heard Frodo beg the others not to use his real name outside the city gates. He has been looking for them and warns Frodo to avoid displays like the recent one downstairs. He has also seen the black riders.
"'An account of your performance would be very interesting to certain people. After that they would hardly need to be told your real name. It seems to me only too likely that they will hear of it before this night is over.'" Book 1, Chapter 10, pg. 206.
Strider again asks them to let him accompany them as their guide so that their journey can be made without running into any more black riders. Sam doesn't trust him but Frodo disagrees. Strider is happy that they are being more cautious than they were downstairs. There is a knock on the door and it is Barliman. He tells him that months ago Gandalf gave him a letter to be delivered to a Frodo Baggins from the Shire. He tells them to be wary of rangers and Strider shows himself from the corner. Strider snaps at the innkeeper and tells Frodo that the black riders come from Mordor. The mere mention of Mordor shakes Barliman. Strider warns him to forget he ever heard the name Baggins and let them be on their way. They decide to leave early in the morning and Strider tells Frodo to open the letter once Barliman has left. The letter, in Gandalf's hand, tells them that they may meet Strider, whose real name is Aragorn and they should trust him. Frodo asks Strider why he didn't mention his relationship with Gandalf to begin with and Strider says it wouldn't have mattered. Sam doesn't believe that Strider is the same man mentioned in the letter. Strider gets frustrated and tells them that if he had wanted to kill them and take the ring he could have done it already. Aragorn's sword Elendil is broken a foot from the hilt. He says it will be re-forged in due time and then that they should make their way to a half way point between Bree and Rivendell, called Weathertop, the next day. He is troubled by Gandalf's prolonged absence and thinks it may have something to do with the black riders. Merry rushes in with another Hobbit and tells them that they saw black riders outside and followed one. Strider worries that the riders are bold but is sure that they will not attack that night. Regardless, the hobbits sleep on the floor in the common room and Strider watches over them.