Chapter 69: Family Reunion

Tropes That Appear In This Chapter:

The Battle Didn't Count: Arny doesn't think her defeat to Isabela is enough to break her vow of silence because "witchcraft is cheating."
Berserk Button: Since family is Serious Business for the Madrigals, Mirabel is a lot more pissed at Valka for leaving her son than Hiccup is.
In Spite of a Nail: With the exception of Mirabel being there, Hiccup's reunion with his mother Valka works out about the same as it did in How to Train Your Dragon 2.
Irony: Hiccup highlights the irony that Valka left Berk because she thought that without her in his life, he would be a normal viking and not a dragon-lover like her.
Like Parent, Like Child: Played for Laughs. When the Madrigals remark on Valka's eccentricities (and her rather feral behavior), they all see the resemblance Hiccup has to her.
...instead of taking her hand, Valka instead chose to stalk around her. Leering, and even sniffing at her. Looking more like a beast at times.
This was Hiccup's mother?
...
In a way, it sort of makes sense.
LOL, 69: While the chapter averts the "Bizarro Episode" commonly applied to episodes and chapters that comes out on April Fools' Day (which is when this chapter was released), HotPatooty appreciates the Contrived Coincidence that it was the 69th chapter.
This Is Reality: When Hiccup tells Valka that actual magic exists in the Encanto, she insists that magic isn't real. The Madrigals immediately prove her wrong by demonstrating their gifts.
Too Dumb to Live: Eret and Arny might not have know where their new enemies lived if Tuffnut didn't keep shouting "Berk Forever."
Wham Episode: The chapter ends with Hiccup and the other Madrigals accidentally bringing Valka back to the Encanto.