Their plan was simple, and everything went perfectly as they managed to capture the Serpent. Leona and Grant were in charge of the interrogation because they were worried that Havok would end up inadvertently killing the Serpent which would lead to another headache for their group. They had plenty of enemies, so they did not want to add the 5 families to that list. Not because they were weary of them, but it was just unnecessary.
The Serpent was reluctant to say the least, but he realized that there was no escape with Havok sitting on the other side of the room keeping an eye on him. Once he calmed down, he realized that they just wanted to ask him questions. After that he cooperated fully. Since he was not directly related to the topic at hand, he was not forced to sign a 'Core Contract' like the few others who knew about this sensitive information.
