Thank you to @LatiasProductions for your input and names.
I do plan on using the name Robin later on in my book, it just didn't seem like a fit for a Night Fury.
However, Delta's children's names will be (in order of birth):
Nightengale, female. My inspiration from the name Robin, they are both songbirds (I don't actually know if Nightengales are nocturnal but I didn't want to use 'owl' as a name.
Blackmoon, male. Tribute to Hiccup because that was his cover name in book 1.
Night, male. @LatiasProductions gave me this name and I really wanted to use it.
Vera, female. Comes from Latin and means true, although I'm going to pretend it is Norse cause this is Vikings we're talking about and they spoke Norse.
Oh! One more thing. Delta's children will be shapeshifters just like their mom.