So, it seems that every possible ending has Triss alive and well, whatever you do.
What do you think, why is that? You have to butcher entire camp to save her or they just let her go. Why Letho sets her free? Is it just a cheap way to make sure that she is alive in every possible save import? Or there is more to it?
Maybe Tress have been working for Nilfgarad all along? Her being chained just a minor disagreement? After all she spent awfoul amount of time talking to that Nilfgarad merchant in the first game.
Or maybe Nilgarads just had time to put some mind control spell on her, then order Letho to take her to Geralt?
What do you think?

One thing that you can take to the bank:

The Scooby gang (Triss, Zoltan, Dandelion) never dies.

Maybe Letho was just being a pal, since prioritizing the White Flame Dancing on the Grave of His Foes's jobs were no longer necessary at that point.

Letho said that he was never an enemy of Geralt. They used to be kinda pals, or at least travelling companions. Framing Geralt was unintended as he wasn't expecting Geralt to be by Foltest's side. Ultimately, his job was to assassinate a few kings by any means necessary. By the end, his job is done, might as well save Triss as a sign of goodwill, or a peace offering of some sort.

Yeah, I agree. It's mostly this. It doesn't really bother me, though. The nature of Triss's role in the story and her relationship to Geralt still changes depending on what you do. It's fairly subtle, but that's fine after all the big stuff.

My take on it was similar to vAddictedGamer in that it is more of a peace offering. Letho, Serrit, and Auckes all say or imply that if Geralt had his memory and decided to stop them, they would be stopped. Remember Geralt is the most powerful witcher out there because he is the only who who has survived what I guess is the second tier of alchemical enhancements. Letho makes it a point on several occasions to tell Geralt he isn't his enemy, but talk is cheap so he shows it at the end if you decide not to rescue Triss yourself.

The interesting thing would be to data mine the decisions made by players.

Consider an option in which Triss can really die?
How many people would actually choose to save her over supporting Roche in search of Foltest’s daughter (as an example)?

This also might very well be a canonical decision with an insight into a future of the series.
Consider other games and choices they make for you in sequels or characters from your party that cannot die.
Mass Effect will only allow you to kill off two characters out of party of six,
Then it forces you into working with Cerberus regardless of what choices you made.
So it is not that unusual…

Sometimes it just might be better to limit the options for the sake of the story (not that I am implying that ME2 had a story)...

Though in the end I am glad Triss is fine, she is a great girl and I look forward to seeing more of her in games to come :)

Perhaps it's just another play on player's expectations. Just how many of us went to find Anais/freed Philippa instead of saving Triss the first time around? Probably not many.

Each decision will uncover a new piece of infofmation. Save Triss and learn more about the Lodge, save someone else and learn more about politics + Letho surprises you by saving Triss. It goes to show that what you think would be the 'best' choice may not be the best choice after all.

As to why she doesn't die, cbarbagallo was right when he said the Scooby gang doesn't die ;)

I hope that TW3 will be maked sooner or later, and developers just had to limit number of factors influencing next part. I think it will be hard enough to include all possible endings.

It made no sense to me that Letho would save Triss and jeopardize his standing with Nilfgaard.

While he doesn't see himself as Geralt's enemy, they aren't exactly best pals either. And Letho already stuck his neck out once for Geralt's woman. Now his well-being and the reopening of the Viper School could all go to hell, nullifying all his efforts.

If she'd actually die, I would never save her manipulating ass. I chose to save Foltest's daughter, without knowing if Triss would survive; I couldn't care less.

I think Triss being alive at the end of TW2 has significance for TW3 or whatever expansion packs CPRD has in development. It will probably involve her relationship with Yennifer as well as her relationship with Geralt.

Honestly, I don't think the emperor gives a shit about what Letho does at this point. The latter has done his job, killing a few kings and wrecking a havoc among the kingdoms. If the emperor wants Letho killed or refused to rebuild the Viper school, whether Letho saves Triss or not fighting Gerald would not make much of a difference.

It's an easier decision on the Roche path. There's a child in danger. If Triss knew why Geralt wasn't coming for her, she would understand.

It's more difficult on the Iorveth path. Only when Geralt learns that he can save Saskia by springing Phillipa does it make any sense for Geralt to fetch that [female dog].