I wonder why the Allies did not execute or imprison Napoleon in Bastille for life after both times when he was captured. Even more, they risked by granting him an island in possession. This is quite illogical given that they portrayed him as an evil murderer and usurper.
Only two reasons come to mind in this light:
That they did not want to create a precedent of murdering a head of state so that they not to be murdered similarly in case of defeat.
That they somewhat recognized Napoleon as a legitimate leader or at least recognized something of his impact as positive.
May be there were other reasons, for example, the Catholic church did not want to revoke the title of emperor from him?
What were the actual reasons?