Reading through the Allistair-Zevran dialogue on the wiki makes it even more clear that Zev did not plan to survive that encounter with the Wardens.
*Spoilers below*
* Alistair: So why would the Crows send you, Zevran?
* Zevran: Is there some reason why they should not?
* Alistair: Plenty of reasons. Starting with the fact that you weren't exactly the best they had, were you?
* Zevran: Slandar and lies. For shame, Alistair.
* Alistair: I'm not an idiot. Well, not most of the time. You're no raw recruit, but I've seen you fight. You're no master of combat, by any means.
* Zevran: Assuming that I intended a fair fight, that would indeed be a problem.
* Alistair: But the Crows must have master assassins, the way you describe them. Men with years and years of experience. Why not send them?
* Zevran: Why not, indeed? It is a mystery for the ages.
* Alistair: Oh, I get it. You're not going to tell me.
* Zevran: Morrigan said you were sharp. No liar, she.
--
* Zevran: Still with the stern glances, Alistair?
* Alistair: You didn't answer my question. About why the Crows wouldn't send their best man.
* Zevran: So for that I must suffer all these fearsome glares? You are cruel to subject me to such torture.
* Alistair: If you aren't telling me, there must be a reason.
* Zevran: If you must know, the masters do not often take contracts outside Antiva. And I made the best bid.
* Alistair: Best bid?
* Zevran: We agree to pay the guild a portion of whatever the contract offers. The one who agrees to pay the most gets the contract, so long as the guild deems them worthy.
* Alistair: And they thought you were worthy?
* Zevran: Against a pair of Grey Warden recruits? Apparently so.
* Alistair: Were there many who wanted the contract?
* Zevran: None. You are still Grey Wardens, after all, and even in Antiva, killing members of your order is considered... impolitic. It made the guild's decision considerably easier, I imagine.
* Alistair: Well, that's comforting, somehow.