…Avalanche’s ethnicity?

While the Official Handbook of the Marvel Universe Deluxe Edition #1 revealed that member of the second Brotherhood of Evil Mutants, Avalanche, was Greek and his name was Dominic Petros…

…when seen without his mask in Uncanny X-Men #141 he is clearly not of that ethnicity…

…and in Uncanny X-Men #223, Claremont reveals his real name to be Domenic Szilard…

…this surname, plus the spelling of “Domenic” indicative of his being of Hungarian descent.

In UXM #255, Claremont further reinforces the Hungarian connection by Avalanche being referred to as Janos…

…so I’m assuming he intended his full name was Domenic Janos Szilard.  The surname Szilard means “solid, firm” and is the Hungarian vernacular form of Constantine.

Sadly Fabian Nicieza goes on to cement OHTOMUDE #1’s faux-pas in continuity…

…a fact sadly held to since.

So now to my No-Prize explanation:

I would posit that Avalanche had a Greek passport under the name Dominic Petros, but it was just an alias.

As to why he travelled to and from Greece?!

In X-Treme X-Men #4, when searching for Destiny’s Diaries, Ororo finds her will in which it is discovered that she has left Rogue as the sole heiress of her estate…

…and in X-Women it is further revealed this inheritance includes a villa on the Greek island of Kirinos.

So how long had Destiny owned a villa in Kirinos?

I would posit she had at least owned it before the second Brotherhood of Evil Mutants had gone public in Uncanny X-Men #142, and that the island hideaway had acted as a private training location for the team…

…Avalanche putting his powers to the test there without much external monitoring.

That is, the Cyclades chain of islands off the coast of Greece is known for regular earth tremors, so any such ones produced by his practice/ training with the team would not have been suspected as caused by a mutant.