@eng1 Having spies and a spy that directly caught the eye of the prince and was able to gain his trust is an entirely different matter. Plus you need multiple sources to avoid wrong information, it’s always good to have more spies.
The second prince will never become the successor as long as it’s the Emperor’s choice. He was not considered a prince to begin with.
The second prince only has 1/2 of the army and the best part is with the emperor so even if the crown prince dies he wouldn’t be able to attack the palace, with the first prince on the other side.
Another possible scenario is that the first prince expected the second to use her to do a secret mission in the palace since he probably knows that the 2nd’s mother is in a bad situation. In that situation the MC could kill the mother, and make it seem like it was the emperor’s deed. It would force the 2nd to fight the emperor as revenge and divide the loyalist army.