Someone on Tumblr wrote about their headcanon idea (sorry I can’t find this post) where Tintin starts to develop Haddock’s form of soft-swearing, and I’d like to point out that this is indeed canon.
Above, Tintin insults two guys by calling them “ostrogoths” in The Calculus Affair.
Haddock using it as an insult:
@katy-133 The nice thing is that it actually matches the original version in French!
Even though Haddock’s vocabulary was already rich and diverse before meeting Tintin (easily noticeable when reading The Crab With the Golden Claws), this canon is actually really nice, considering the fact that Tintin has influenced Haddock a lot with his scout-like habits and values.
Haddock’s vocabulary is such an interesting part of the Tintin world!
(They actually made a whole dictionary of his curses and insults (only in French): https://fr.wikipedia.org/wiki/Vocabulaire_du_capitaine_Haddock )