Pharaoh's Free Will

The Ramban in Parshas Lech Lecha asks how did Pharaoh have free will and why was he punished for enslaving Bnei Yisrael if Avraham was told by Bris Bein Habisarim that Bnei Yisrael would be enslaved. What choice did Pharaoh have? It was decreed earlier by God that he would enslave them?

Ramban first quotes Rambam's answer that it didn't have to be Pharaoh himself it could have been another king or another dynasty. Ramban doesn't like Rambam's answer for various reason's one of them being that if God decreed that someone should enslave Bnei Yisrael then it should be looked upon as a Mitzvah and Pharaoh should have actually gotten rewarded for it, what does the Rambam mean that someone else should have done it?

Ramban answers that although it was decreed that Bnei Yisrael should be enslaved, Pharaoh went beyond the call of duty and also tortured them and threw the babies in the river. Since Pharaoh did more than he was decreed to do he was punished.

The question is why was Pharaoh then punished for enslaving Bnei Yisrael, he should only be punished for going above and beyond. Pharaoh should only be punished for throwing the babies in the river and torturing Bnei Yisrael but not for enslaving them?

Maybe in fact, and it is a bit implied in the language of the Ramban that in fact Pharaoh was only punished for what he did more than what was decreed. Ramban says the pasuk states

וְגַם אֶת הַגּוֹי אֲשֶׁר יַעֲבֹדוּ דָּן אָנֹכִי וְאַחֲרֵי כֵן יֵצְאוּ בִּרְכֻשׁ גָּדוֹל
The Pasuk states "Dan" that there will be a judgement and this implies that there will be a discernment as to what Pharaoh will be charged for and what he will be innocent of because it was in fact decreed.

Another explanation might be that the Ramban is saying that although it was decreed, because Pharaoh did more than was decreed, he will be judged for everything he did including what was in the initial decree. Once it is established that Pharaoh enslaved Bnei Yisrael because of his wickedness and not because God decreed he do so then his punishment will be on everything he did.

We find many times that intent matters when something is done outside the ordinary course. For example:

• By Pilegesh Begivah it says that Bnei Yisrael were punished and many of them died when they went to war with Binyamin because of Pesel Micha. It say "al kvodi lo michisem ve'al kvod adam michisem" Paraphrasing- You didn't care  about my honor and served avodah zara but when the girl was killed in Binaymin you cared"?. Although one might say that a horrific murder is something to stand up to, the point was that you obviously didn't do it for God's benefit since it is apparent that God's honor is not important to you so therefore your killing of Shevet Binyamin must also have been for some ulterior motive and therefore not justified even though the act might be justified, in this context the intent will define the act.
• The Chasam Sofer in his last Tshuva in Orach Chaim states that although "Eis la'asos Lahashem Hefeiru Torasecha" meaning that there is a unique dispensation to write Torah SheBa'al peh and that allows all us to write it even though "Ee atem Rashaim Lichtovum" we are really not allowed to write torah SheBa'al peh however they allowed lest it be forgotten. The Chasam Sofer says that if one writes torah SheBa'al peh without the correct intent he is oiver on this issur of writing down Torah SheBa'al Peh
• Ester Karka Oilum, although Queen Esther was allowed to sleep with King Achashveirosh to save Klal Yisrael the Gemarah says she did not have any enjoyment out of it. If she would have had enjoyment, even though she was allowed to she would not have been considered doing a mitzvah. 
• Shaul with Agag

If someone is mechalel shabbos to save a life. For example driving an ambulance to the hospital on shabbos but at the same time he turns on the radio, uses his phone, smokes a cigarette, this shows that his whole chillul shabbos is not for the right reasons and he can be then considered violating the shabbos for driving too.