This is where it's at for me. I haven't decided which LI I'll really care about, it's the concern that Summer's absence becomes a weak story device, while currently it is a strong one, driving all of Nika's dysfunction. By weaking the main plot device, the story needs something stronger to support the challenges that disruption of narrative flow brings. A couple of scenarios:
- Summer returns, and thanks the aliens that kidnapped her and her family for their hopsitality, the tabletop game was a foreshadowing of the change to the plot. Weak or strong? I can actually think of a couple of VN's that have variations of this
- Summer returns, battling to close the portal to the cthonic realm of chaos. Nika's trauma shows that he is attuned the the elder god's madness and is able to overcome them. Weak or strong?
- Summer returns having escaped from a serial killer who murdered her family. The serial killer is wealthy and hides as a benefactor of MOR university. Weak or strong?
- Summer returns and was put in witness protection, but breaks her cover to reunite. Weak or strong?
All of these (in my opinion) are trainwrecks to what worldbuilding has been established. Summer returning will have to be not only plausible, but visceral enough to feel relevant. She can't waltz in and be on the scene as though the last 5(?) years haven't happened. Some gala at the Holgersons and a chance meeting? Summer would know from Elsa that Nika's still in WOllust, so there will be no chance meeting.
Also, reappearing for Nika, but having left Nia in the dark also? Doubly important to be a very plausible reason, unlike the humorous/sarcastic ideas I randomly suggested. THe plot holes need to be as small as possible if Summer returns.