A question Regarding Kalista's Reveal

Unfortunately I always seem to find out about Q&A sessions after they've finished--my fault, considering I generally ignore the forum and thus miss all of the announcements I now realize are sent out beforehand. However, reading over the Q&A session, I realized that for once I actually do have a question burning a hole in my head. I wasn't sure where to place it since it's a question kind of concerning the mindset behind presenting Kalista as a Marksman, and yet it is more geared towards a particular graphic used in Kalista's Reveal--while simultaneously seeming to reference Kalista's Lore in relation to others. And yet it also seems like none of these things, though I may simply be addled due to posting in the middle of the night after working a closing shift.

http://news.cdn.leagueoflegends.com/public/images/pages/kal/img/kal-screenshot-thumb.jpg

Preamble aside, my question is thus:

With Kalista being presented as a Marksman, what were the reasons behind having her soulbind with Lucian in order to fight against Thresh when Lucian himself is a Marksman? Were they lore related rather than gameplay relevent? Was it a hint at Kalista's relationship with Thresh? If it is lore related, why is Lucian soulbinding with Kalista when he has coldly vowed to end all such tortured existences? I realize he may want revenge on Thresh, but... I just noticed a great deal of mixed signals and wondered if there was anything maniacally clever going on behind the scenes.

I realize this question also kind of concerns the meta, but I realize that the meta is not something Riot enforces so much as works around. It's a useful tool for creating and patching champions, as well as for teaching players essential components of gameplay. A construct of the playerbase, used to create a language of sorts so that players can provide useful feedback and Riot can effectively communicate with the playerbase regarding additions, changes, etc.

Also, I understand if I'm too late to get this question answered. I realized it was kind of a longshot, but it's rare that I have a question I'm willing to spend a few hours learning how to use a forum interface to for and thought that I should at least try.

Without Wax (and regrets!), Devaad

P.S. And yes, I realize the question of whether or not Kalista was Senna was answered by a Rioter already. I just noticed an inconsistency I couldn't explain and realized I was desperate to find out if there was a reason, or simply coincidence.