Bill couldn't kill himself. Of course, there are things worse than death. In an effort to kill himself, Bill could suffer substantial burn damage and be unable to die until Adam intervened. If Adam made every effort to not kill Bill, Adam would eventually kill him by accident. I see your point. I'm just trying to figure out how to get the death of Baldur (i.e. Bill) (which is one of the first signs of Ragnarok) incorporated into the story and make Loki (i.e. Adam) the heroic protagonist. So, throwing a couple of ideas against the wall just to see what sticks and maybe gives me a little more breathing room to address Baldur's death.
Yes. To be more precise, the Aesir and Vanir incarnated on Earth in preparation for Ragnarok. They were born as human babies. The intent was for them to have time to grow into adults before Ragnarok. However, Ymir has been able to get Ragnarok to start ahead of schedule. So, all the gods are in the bodies of young adults. Further, as no human child could withstand the power of a god, the babies were born without knowledge of who they really were. Many of them still don't know who they really are. They are supposed to be hidden on Earth until they 'quicken' and gain awareness of their divine nature. Ymir has stolen a recently discovered relic which contains an unknown prophecy. With it, he can track down these children and kill them before they learn their divine nature and acquire their divine power. So, these gods are basically lambs to the slaughter. Somehow tbd, Loki realizes that he can take the advantage away from Ymir by killing Baldur (which is the first official omen that Ragnarok is beginning).
In my opinion, mourning has very little to do with whether or not one believes in an afterlife. Mourning is about one missing the other person, and learning to cope with one's own life without them being here now. Of course, in this particular story if Adam can still interact with Bill after he is dead and depending on how present he continues to be, maybe you have a point that what does it really matter that he is dead now. For most of us who believe in an afterlife killing is taboo in part because we also strongly believe in the value of life, that life teaches us lessons that should not be skipped. Also there may be an element of doubt there, I admit. It is one thing to believe in an afterlife, but if one can no longer interact with the other person, practically they are gone, they feel gone. That's the other thing for this story, if Adam continues to be there after Bill kills him, would Bill have cause to mourn? Would Adam really feel gone, would there be anything that Bill would miss about Adam when he was alive. And would there be any indication that he missed out on something important potentially due to his life being cut short?
