Find a Reaper Queen, weaken her until she enters the impregnation state, disable nearby charge light, and let her grab you while using a trap, shield, armor, and healing supplies for safety. During gestation, gain experience by defeating creatures while avoiding radiation, then use a Reaper pheromone gland before birth to calm and claim the baby. Raise it in a secure enclosure with plenty of meat, using additional pheromone protection until it becomes juvenile.