Apollo -- Just a bit bleh to me. Not that it's boring, but it's a name like
Rocky; it just feels over the top to me.
Anton --
Love it for someone else's kid. Currently associate it too much with
Gaslight, but I think it's an excellent name.
Ari -- The only
Ari I've known was a girl, but I don't see why it wouldn't work on a boy.
Cai /
Kai -- Handsome, if too current for my tastes. Prefer
Kai.
Leif --
Love it. Would work fine.
Otto --
Love this, too. I don't see why it shouldn't work.
Rune -- Has a great meaning. Getting people to pronounce it with two syllables would be a huge pain in the ass, though.
Severine -- The -ine ending looks very feminine to me. Do you mean
Severin? In which case, I like it, but the similarity to "severing" could be a problem.
Tobias -- Was always my favourite Animorph. ;) Works fine. Definitely a good choice.
Torben -- Reminds me of "turgid" and "moral turpitude." I don't mind it--I love Scandinavian names, on the whole--but I'd rather see something else.
Tyge / Tage -- Another where people are going to pronounce it wrong all the time. Getting two syllables from either in the US will be a pain, and just using it with the wrong pronunciation would be pretty lame.
Ulric -- Doesn't do anything for me; I prefer
Alaric.
Viggo -- Too celebrity-follower, and the sound still wouldn't really appeal to me if there was no Mr. Mortensen.
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