After Time Travel, the Male Protagonist Became My Father's Good Brother

I entered the doomsday novel, intending to be cannon fodder. But surprisingly, I met my dad. He no longer looked like he was in his forties, he looked like a young man in his twenties. What's even more unexpected is that he and the male protagonist became good brothers. What will happen to this strange combination in the context of doomsday? Should we fight side by side, or should we have differences due to different ideas? What role will I play in this? Should we strive to change our doomsday fate, or should we just drift with the flow in this special network of relationships? All this unfolds slowly under the crisis of doomsday.