To tame a reaper king/queen, you need to attack a reaper queen(reaper kings will not work) until she’s is low hp. After that, she will sting you with her tail that will make you pregnant. After you wait a good amount of time, the baby will burst out of your chest. The only way to claim de baby, you need to eat reaper pheromones glands that drops from reapers. Good luck survivors!
For raising if you let the baby kill you while your inventory is full of meat it can pick it up off your corpse if it doesn’t just drag the corpse and hold it where the reaper will run into it as it tries to attack you
I got a low lvl one using a strong bary (10 k hp and 300 damage) and i lvld up that reaper and usednthat reaper to get impregnated from a high lvl reaper, i now have a reaper with 50k hp and does over 1100 damage, and is able to take out several reaper kings on the surface. They are really good combat mounts and seem to be relativley fast. Almost nothingnwill aggro on u and they can bunny hop