Thanks for the info!
As I wrote before, with both lung wings collapsed and some other injuries, Nika had a close brush with death. While it is possible that his injuries stem from an accident or a schoolyard fight (or the spiders decided to rise up
), this is unlikely. It would have had outside repercussions and also mental imprints, which is not the case as far as we know.
Therefor I theorise that he sustained his injuries when Summer vanished, most probably under criminal circumstances.
This is reinforced by the fact that neither Nika nor Nami ever reckon with Summer returning. The game title clearly implies a "gone forever".