@Phoenixflambe  
Too be fair I am counting this as canon with how bad the end was

@Argamis  

 
As said; IDW has not contradicted Hasbro (DHX Studios, but who cares about this?) regarding Tirek in his youth as the story of him and his mentor Sendak happened completely detached from the actions in the show. Instead, “Fiendship is Magic” # 2 had revealed that Tirek was simply too young when he began his path to villainy by extracting magic from others. Everything about Tirek in his later life happened only within the show with few exceptions in the comics like “Nightmare Knights”.
 
It does not have to be “plausible” as long as the action in the fan comic can be interpreted within the canon dimension which includes everything that is subject to license rights by Hasbro, as long as information does not contradict what is established in the show, which in itself can be questioned by “the Word of God” as with Lauren Faust.
 
There was NOTHING about the fanon backstory of Chrysalis that was in violation of the canon, as it happened in a historic gap that was not covered early. We do not know what happened between the “birth” of the changelings in and their ravages of the known world in the IDW comics. We do not know what happened between the escape from the volcano in the comics and the attack on Canterlot in the show. Thus, an artist or writer can have freedom in story preparation without being confronted with “established canon rules”.
 
As this is fanon work, it just means that the fan comic can not enter the canon universe of the ponyverse. Everything about Cozy Glow is fiction as there is 100% nothing about her background, while Chrysalis has very big gaps in her background history with her age by being as old as the royal sisters. The story of Tirek and his father is very close to the canon on a logical basis, but now it seems that the step towards free fiction has been taken.

@Argamis  
Well it’s a fanfic, and to quote an apparent line from Lex Luthor: “I can say without a doubt that there are an infinite number of universes. Some are just like our own…. but for one or two significant events, exactly the same.”

@Phoenixflambe  

 
Good point.
 
About “canon”:  
Any minute detail from the FiM episodes of “Twilight´s Kingdom” overrides any later “HASBRO authorized” fanfic the guys at “Ideas & Desing Works” (I.D.W.) may have cooked after the fact [they never talked with the writting team at DHX].  
-> Even with the “storybook format” animation, is clear they both were full grown adults.
 
I see no point on forcing this story to be as a “plausible continuation” of the Prime Timeline after season 9; since from the “backstory” of Chrysalis this could not be the case anyways [regardless if it is “posible” or not, it is NOT plausible].

@Background Pony #A704  
As far as I know, when they came, they weren’t that young.

@Phoenixflambe  

 
Do not know, we are not in the canon country from the last page, so the writer here may have chosen to ignore the IDW with Sendak. Which may be a mistake, but it’s his own choice - for now the lore of the canon is no longer sufficient. Possibly Tirek will travel straight to Equestria, but then with quite a few logical flaws in the luggage. Regardless, Sendak is essential if this narrative is to be within the fences of what is canon. If Sendak is absent, the fan comic will thus become one of the many fanon universes in the ponyverse. Maybe No. 16 in the ranks away from the prime world.

Are they visiting Sendak?

Wohoo, road trip!
 
I’m sure nothing bad will come from this.

Monsters are made, not born.

And then it begins.