Why would the Viking be a cat?
Because inside every Viking is a little ball of fluff.
A ball of fluff capable of amazing feats of athletical prowess and the constant urge to quench the burning bloodlust within.
Cats are cutw but they are also evil.
Why can't we use "on" when referring to a specific thing here?
That's the thing i keep screwing up too.
Because it's a question and there is no question word so the word that is asked for gets the -ko suffix.
The Viking is crying now
Normaalisti sanovat onko kissa viikinki?
Then it would be Is the cat a Viking?
It is strange with a capital V on Viking and with ”the” Viking.The sentence becomes nonsense that way!