I would like to open up a possible debate, if it's possible, concerning Rinne. Her personality shift and motivations are probably one of the biggest open mysteries the first episode has set up, and depending on the answer, we probably are going to get a rather dark series, or a series who conflict stakes are fairly low, pedestrian and part of normal growing up, such as Vivid. So far, I've seen two theories about what caused Rinne to shift - the first theory is mine, which suggest that Rinne might be another victim of Project Fate, and the second is
KarrinBlue prize-fighter/abuse theory. I think there's an interesting theoretical discussion that can be had, as to what made Rinne change when she was adopted, and I wonder if anyone has other theories on that matter?
I'd like to start by offering my take on KarrinBlue's "Underground adopted/slave gladiator theory" .
The key problem I have with the theory is that Rinne is competing in former, official tournaments and is highly exposed to the public eye because of her activities in the Strike Arts. Now, it's possible that one alternate variant is a replacement Goldfish theory - the Berlinetta's had a daughter who was a Mage and champion Strike Arts fighter, who unfortunately died young in an accident. So, the Berlinetta's looked for an orphan that best fit their dead daughter's appearance and skill-sets. Keep in mind that Mage is not necessarily an occupation in the Nanoha-verse, and one could easily be a fashion Mogul and a Mage - indeed, given the implications and potential customization of barrier jacket, being a Mage might be an advantage in the fashion business!
But the second reason why I am dubious that this is a straight-forward case of rare-skill adoption, is because all previous Nanoha-verse works generally run on two thematic conflicts - Artificial human beings/Mages (Original, Striker S, Force) and Walking Lost Logia/Lost Tech designer baby lineages (A's, Vivid, Striker S). I wouldn't be surprised if Fuka and Rinne's conflict is going to be intimately connected to either or both themes. And if those two themes are indeed present in Vivid Strike, it's quite likely that Vivid Strike is going to be a more serious,, higher stake series than Vivid is. There are ways for Rinne to be adopted by well-meaning foster parents, and yet turn out screwed up as a result of the adoption, if either Walking Lost Logia or Artificial Mage is involved with Vivid Strike's new cast.
P.s: I didn't see Lutecia in the OP. But since Fuka is going to get an Intelligence Device, I wonder whether Lutecia would make an appearance again in Vivid Strike as the Device Meister who will create Fuka's device. Or whether she won't appear, and Fuka gains her device from Einhart "as a gift" Einhart procured "from her contacts".