Letterman called Colbert "always entertaining," "the new kid" and "my friend." What Letterman was saying, implicitly, was that he supported CBS's pick for his successor.
CBS announced that it had signed Colbert to a multiyear deal back on April 10, one week after Letterman revealed that he intends to retire in 2015.
The unspecified timing of the transition came up during the chat between the two comedians. When Letterman asked about family matters, Colbert, who has three kids, said, "They're getting ready for me to hang around too much." He pointed out that he'll be signing off his Comedy Central show "The Colbert Report" at the end of the year, "and then there's -- I don't know -- when are you leaving? I should have asked!," Colbert said as Letterman laughed. "I should have asked."
"The thing is," Colbert said, getting back to his family, "they get nervous, they get nervous. I think they like me, but they get nervous when I'm around too much."
Colbert appeared as himself, not as his "Colbert Report" character. Tuesday's "Late Show" visit is likely to be the first of many media appearances that introduce the "real Colbert" to viewers.
Colbert also styled himself differently than he usually does on the "Colbert Report," further distinguishing between that show and his next late-night act. Instead of glasses with invisible frames, he wore hipster frames, for instance.
"You look good," Letterman said as Colbert came on stage. "You look right at home."
Colbert showered praise on Letterman, and remarked at one point, "I'm gonna do whatever you have done." When Letterman responded with mock disapproval, he added, "It seems to have gone pretty well, Dave!"
"It's, it's gone ON," Letterman said.
During the two-segment interview, Colbert talked about how he applied to be an intern on the "Late Show" in 1986 and submitted a writing sample for a job in 1997. "I was unemployed at a professional level," Colbert quipped. By the time he heard back from the "Late Show," though, the show that became "Strangers With Candy" -- which Colbert co-created and starred in -- was in the works.
True to "Late Show" form, Colbert read what he said was his actual writing sample from 1997: a "Top Ten List" titled "Top Ten Cocktails for Santa," with inventions like "Mama Said Nog You Out," "Scrooge Driver" and "Jack Frost."
When the "Top Ten List" animation played on screen, Letterman joked, "Wait a minute! He doesn't get that yet!"