Big-Boobied Bertha is the mother of Camicazi. She is also leader of the Bog-Burglars. It has been told in the books that her boobies had killed before and many a smaller animal had suffered in their depths.
She first appeared in the book How to Speak Dragonese. The first notification we have of her is the letter she writes to Hiccup's father Stoick demanding the return of her heir and threatening an outbreak of war if she is not returned within two weeks.
The next time she appears is when she believes that Stoick is running away from her proposed war instead of looking for a Roman Fortress to rescue his son Hiccup. Bertha is delighted when Camicazi is returned to her by way of a Roman Observation balloon and by way of apology she returns the shield of Grimbeard the Ghastly that the Bog Burglars stole generations before.
In this novel Bertha's only appearance is her attendance of the Freya's day Friday celebrations on the Isle of Berk.
In this novel Bertha attends 'the thing' (a meeting of all the Viking tribes) where it is mentioned that she had some of her reindeer rustled a couple of months ago by Grabbit the Grim.
Big-Boobied Bertha later launches her ship The Mighty Momma in order to search for her daughter. Bertha in the Big Momma and Stoick in the Blue Whale join Camicazi, Humongously Hotshot the Hero, and Fishlegs to pick up Hiccup and all were extremely worried. Upon departure Bertha leads her tribe in song echoing the Hooligans as they sail away back to Berk.
In this novel Big Boobied Bertha and her tribe join the Hooligans in a three day pickpocketing contest. Bertha and Stoick make a bet on two of their finest axes that their tribes is the better one at burglary after Bertha insults Hooligan ability.
Bertha is keeping her Stealth Dragon that she stole from Madguts the Murderous in a Hooligan stable which is later stolen by Hiccup, Camicazi and Fishlegs for their trip to the library. Big Boobied Bertha attempts to show off her ability at burglary by showing Stoick her Stealth Dragon but this plan backfires when they are cornered by the Hairy Scary Librarian.
Bertha and Stoick try to talk their way out of it but are rebuffed by the Hairy Scary Librarian. Fortunately Hiccup arrives and squashes the Librarian flat by the Stealth Dragon and when Madguts arrived he blamed the Librarian for Bertha's misdeeds. Madguts believes Hiccup's lies that the Librarian was the thief and that Bertha was apprehending him before he arrived. Madguts gives Bertha a sword as a reward for her troubles.
Bertha lost her bet against Stoick due to Hiccup's actions in the stealing of the book from the library and the stealth dragon and stumps up two axes for Stoick. On the way to the Hiccup's Birthday Banquet Bertha starts a new bet that Bog Burglars are the better fighter and bets two of her finest swords.
In this novel Bertha and Stoick are tricked out of the race by Madguts who leads them to believe that the race starts when you start swimming and that leaving the water would be fine to so they could have some of his Deepest Purple Fleshfang Oil.
Bertha and Stoick are later imprisoned by Madguts who demands that his prize should be the Kingdoms of the Hooligan and Bog Burglar islands and that Bertha and Stoick should be picked to death by Sky Dragons. However as the judges are unsure whether Camicazi, Hiccup and Fishlegs will return and thus be the rightful winners of the swimming race instead of Madguts, Bertha and Stoick are imprisoned awaiting the agreed date for Madguts to claim his full prize.
Bertha and Stoick are released when Hiccup, Camicazi and Fishlegs returns and Hiccup is made the last man back making Madguts's claims void. Before their arrival Bertha and Stoick were preparing to show how a Chieftain should die with pride.