I croaked, “Titania wants Marcone dead?”
I don't see how it could be any clearer. But if you insist.
“Why?” I asked him. “Why would Summer want Marcone taken by the Denarians? Why would Summer want the Archive under their control?”
The gruff only stared at me for a long moment, but when he spoke I could have sworn that his voice sounded pensive. Maybe even troubled. “It is not my place to know such things—or to ask.”
Titania wanted Harry dead.
“But it’s over,” I said. “Marcone is already free. So’s Ivy.”
“But thou art still here, upon the field of conflict,” the gruff said gently. “As am I. And so the matter is not closed.
Titania is crazy with grief and doesn't care what happens to the Archive or Marcone or to anything else. And so she tells Harry in Cold Days. And once he leaves the island it ends.
This arc starts in Summer Knight with the death of Aurora. Continues in Dead Beat with Marcone saving Harry in the alley. White Knight with Marcone becoming a Signatory, and finally ends in Small Favor.
Edit
this is very confusing having two similar conversations at once.
I see the Fae Courts differently, evidently, than most of the people here. To me they are modeled loosely after the Russians and the Americans and the Cold War. In that kind of context the behavior of the Queens in Small Favor make perfect sense. The attempt to suborn the Archive and to kill Marcone is a proxy war. The goal is not directly connected to the direct conflict, killing Marcone and taking the Archive. The point is to take revenge on Harry, Mab's Emissary in the matter of Aurora's death. Jim blows smoke by distracting you with an ever increasingly large set of Gruff's until ending with a diminutive Eldest Gruff. And a sideshow about Mab taking Harry fire magic.