The Witcher 2 ending

There are combination of endings that can be achieved that will change various things in the meeting and the ending. Nothing in chapter 1 will effect the ending.

Roche's Path
If you decided to kill King Henselt then the meeting in Chapter 3 will.....

If you let him live, Henselt doesn't only have Upper Aedirn but whole of Aedirn will be given to him as there isn't anyone left to ascend to the Aederninan throne because prince Stennis dies in the ghostly mist.

If you went with Vernon Roche to save King Foltest's daughter, Anais, and you convince Roche to give the Anais to Temeria. Then Roche wil say that she decided to pick up a sword instead of a doll, and will be a great leader.

If you went with Roche to save King Foltest's daughter, and you convince Roche to give the daughter to Radovid. She will grow up to marry Radovid and Redania will protect Temeria for the time.

In the Epilogue, If you went to save Triss yourself, then on your the path to see Letho, You will see Roche saved Anais by himself and is defending her from a bunch of soldiers. You will save him.

Iorveth's Path
If you decide to save Philippa Eilhart, then you will be able to release dragon from her control. You will not be given an option to kill her.

If you decide to save Triss instead, then you will be given an option of killing the dragon or leaving it. Iorveth would've went to save Philippa and then get badly hurt by her. You will be given the option to walk away and leave Iorveth to the troops, or attack them and tell Triss to save her. She will say that he is badly hurt and will take months to heal him.

Shared Choices
If you saved Sheala de Tancarville, Letho will mention she will be hunted by Royal witch-hunters and die a slow death by them. If you let her die, then Letho will say you showed her mercy.

In both paths, if you save Triss instead, the Council of Sorcerers will still be created, since Triss is the one that pointed out Sile was the traitor.

If you did not save Triss, she will be saved by Lethos, Shilard Fitz-Oesterlen will point out Sile as the traitor and the Council of Sorcerers will not be created, as people will be hunting witches from then on.

Ending Sequence
If you go with Roche/Iorveth in Chapter 3, then you will walk out with Roche/Iorveth and Triss.

If you go with Triss, you will walk out with Triss only.

After the run up through the tower to get to Sile, if you fixed the scope crystal, then Letho will comment how you are giving Sile a worse, slower death, being hunted by the Royal army. If you did not fix the scope, Letho will mention this is a better death than at the hands of the royal army.

After fighting the dragon's Quick Time Event, if you decide to kill the dragon, then you will reason later explaining that it was enslaved by Lodge and will keep doing their bidding. If you did not kill the dragon, then you will reason later explaining that dragons are rare and they are great animals.

Ending Plot Summary
No matter what, Nilfgaard will be on the march north to invade the northern kingdoms. Lethos was employed by Nilfgaard to kill Kings in the northern kingdom to soften them up for the later invasion. Letho used the Lodge of Sorceresses as a cover to kill the Kings because they initally had the same objective.

Lodge of Sorceresses initally only?? wanted to kill Demavend because he was shown to be a weak King. But after his death, Letho used Sorceresses' resources to get in contact with Scoia'tael to kill King Foltest and King Henselt. After the death of Foltest, Letho split with Iorveth and went into hiding, Letho couldn't trust Iorveth anymore as Iorveth and the Sorcereses figured out Letho's true plan.