If you pay close attention on your re-read, it's given away during
House of Chains.
1) He's Napan, with a Malazan accent, and he, "Died long ago" according to himself (chapter three)
2) The quote starting chapter four, the chapter after you meet Keeper, "Has a drowned Napan's body ever surfaced?" [we know that all of the Napan's "drowned" when Laseen came into power]
3) Tavore talks to Nok and Gamet in chapter five about how the Napans all disappeared when Laseen came to power [Urko Crust, Cartheron Crust, and Ameron]. We know for sure that Keeper can't be Cartheron, as we met Cartheron Crust in Deadhouse Gates and he certainly doesn't fit Keeper's description
4) This is what really puts the nail in the coffin: Chapter 11, when Stormy and Gesler talk about Urko punching. "I once saw Urko punch down the side of a mudbrick house... That Napan bastard could pack a punch." Given how tough we know Karsa is, yet how easily Keeper knocked the shit out of him with a single punch, this conversation pretty much gives it away.
It never is definitively said in
House of Chains, though. On a reread, all the clues make it seem really obvious, but the first time through it's definitely easy to miss. Hell, I didn't catch Traveller's identity the first time around, and that was a hell of a lot more obvious than Keeper's. Nearly as obvious as when Quick Ben, Kalam, Tattersail, and others are speculating about the Deck of Dragons and how the Shadow Realm and its two new rulers only came into play after the assassination of the emperor and Dancer during
Gardens of the Moon quite obviously tells us who Shadowthrone and Cotillion are (it ended up just being a mind-blowing surprise in
Deadhouse Gates when Apsalar is recalling Cotillion's memories with Crokus and Fiddler).
This post has been edited by Defiance: 06 January 2012 - 06:49 AM