so whats up with lux

Most likely Garen's.

Not only is he her brother, but Sylas manipulated and betrayed her trust.

I think Lux will represent the path in between, a harmony of sorts.

I feel that Lux is able to understand, and has experienced both sides of this oppression against mages. On one side she is a Crownguard, an elite Demacian and therefore is supposed to be anti-magic. However she is a mage and she knows what it is like to have to be hidden away and hide who she really is.

So from that I would guess Lux can understand Sylas' view and those of other mages. However Sylas did trick her and make a fool of her, but I think Lux would be able to understand why he felt the need to do it since she feels imprisoned herself. So she can see the dangers of a rogue mage, but she also knows what it's like to just be a "normal" person who happens to be a mage.

She was manipulated by Sylas. She realizes what she's done now and has to decide what to do next.

She's on Ezreal's (or Jarro Lightfeather's, whichever name you prefer) side

Why would she ever be on Sylas side? He's a murdering maniac. Lux needs to be Xavier to Sylas' Magneto.