Novel's readers.. I wanna spoilers about Vermouth, the promise he did and spoilers about w...

Novel's readers.. I wanna spoilers about Vermouth, the promise he did and spoilers about what happened in the past and in the future that involve Vermouth and Hamel plzzz
All the spoilers talk about who he end up with and i couldn't find anything about Vermouth and Hamel'a relationship. I feel that Vermouth really treasured Hamel as a friend and companion and was the most affected by his death. If you have any spoilers about it plz share