A couple years back I was pushing pretty hard for Tilly's return. I'd still like it if it turned out he's become a kind of FBI equivalent to Murphy after Changes, and showed up at the Peace Talk summit to speak up for vanilla mortals. Double fun points if his attendance was sponsored by Baron Marcone, because it'd be wonderful to see Tilly gritting his teeth to cooperate with "villain, scum" for the greater good.
+1 for Tilly, for all the reasons you say.
Also: I just
like the character, and I want to see more of him!
I think we're also due for an Elaine visit (overdue? I can't remember anymore. I'm getting old.)
From her own motivations, I think Elaine wants to stay off the radar, and would avoid a high-powered, high-profile event like this, if at possible!
Of course (as we see from Harry's life!) sometimes a young wizard's "own motivation" to avoid certain situations don't line up with "what's possible!"
Haven't seen Billy since Ghost Story and Georgia since Turn Coat, so it wouldn't surprise me if there was an Alpha presence. I can picture Harry calling them up to act as a secret backup plan. On the other hand, this is exactly the kind of attention Harry was trying to keep them away from, so... maybe not. Though I think Peace Talks may devolve into an All Hands on Deck situation.
The Alpha's are "only" a pack of werewolves. They make a decent physical threat, but are too much at risk from other powerful players with mental/magical forces. I expect Harry will want to keep them off-stage, as they're outclassed.
Things WILL go to hell, of course, and an "AHoD situation" (with the Alpha's coming in) is entirely likely.
As others have pointed out, Mavra is a possibility. Especially since the Black Court is a signatory.
Hrm... It's not clear to me that "the Black Court" exists any longer as "an entity" to be "signatory" to the Accords. Maybe individual Blampires could sign on? Most of them are pretty powerful -- survivors of the Stoker purge -- other than whatever scourges/lesser vamps they have created since.
Their power -- as a group -- is apparently broken. Mavra (or any other Blampire) couldn't credibly claim to represent the Black Court, or reliably negotiate / make commitments on behalf of the BC.
HOWEVER... At the end of Dead Beat, Harry threatens Mavra, tells her never to try to use his friends against him, because... now he knows how to use Kemmlerian Necromancy against the BCV's. But she's a reasonably powerful sorceress in her own right (tutored Bianca, who was able to survive a full-power strike of Harry's), and now Mavra has the
Word. So presumably now, SHE knows how to use Kemmlerian necromancy... which may well have given her the edge she needed to re-unite the Black Court, with herself as Black Queen. I can see her showing up in that capacity!