Undead*(kinda like those soldiers anduin resurrected)
Jaina isn't in the cinematic, she's in the trailer and we know she's gonna be the aggressor across the island, while it looks like Genn is the aggressor on land(and in Legion)
And no, I don't think Anduin is an aggressor at all, he's the kind of character that would ask Sylvanas to be his friend after she murders a whole town of people, just like he wanted to be friends with Garrosh. I do think that he is being manipulated by Genn and Jaina and needs more Velen in his life.
And what book excerpt are you talking about? We see here, that the Alliance is outside Undercity and we see the Tauren, Trolls and Saurfang defending her, the same group that turned on Garrosh for his warmongering and evil deeds. If we focus on her actions of fighting the Legion and trying to save her people, while Genn and that admiral wasted good soldiers to try and kill her... we'd see the alliance is evil and would risk jeopardizing the world over a grudge.
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it's ok, there's a giant metal fortress underneath it :P