1- Go to Doom fort and do all of his quests until you are rewarded with the Musket.
2- Go to Milo and do his quest until you reach Adam, just talk to him and tell him that you did some "Old job" with him.
from this moment Adam will be saved from dying needlessly and you will be able to meet him in 2 future quests, altho he is as of now in the current story development... Not needed to be kept alive.