At some point before the Dragon Riders arrived on Melody Island in "Imperfect Harmony", Lil Lullaby was captured by the Death Song and encased in amber. Earsplitter escaped, although he would not leave the island until he had rescued his son.
After freeing the rest of the Riders, their dragons, and Toothless, the gang were about to leave, when Hiccup noticed the infant stuck in a block of amber, which was why Earsplitter was still on the island. While Hiccup distracted the Death Song, the rest of the group freed the baby Thunderdrum from the amber.
In the skies over Melody Island, Earsplitter and his son had a touching reunion. Hiccup warned them to leave the island as soon as possible, but Tuffnut pointed out that the Thunderdrum pair couldn't hear him, as they have very bad hearing.
Lil Lullaby appears similar to other adolescent Thunderdrums, such as Bing, Bam, and Boom. He is blue in color, similar to Bing and Thornado, though he has a slightly lighter, paler blue color than both.
- In Dragons: Rise of Berk, Lil Lullaby has a bit of amber from the Death Song's attack stuck on his neck, while, in "Imperfect Harmony", he got it all off. This could have been added to differentiate him from the other Thunderdrums in the game.
- Lil Lullaby currently has the longest hatching time in Rise of Berk, 14 days.
- Lil Lullaby's avatar is smaller than other Thunderdrums. This could be because he's a baby, but Bing, Bam, and Boom are normal size, despite the fact that they're babies themselves.