The queen will not impregnate you when she is under the Charge effect. Bring her to low health, put all chargelights off, and tank her approximately 1-2 minutes. Works 100%. The level of the queen is important for the Level of the baby. A level 150 queen will give you a level 150 baby. With leveling while the baby is in the stomach, you can get a 225 baby reaper king!
In order to get a reaper king, you must find a queen, found in Halls of the Reaper Queen, then you must hit it
via Rock Drake or ballista turrets until it has a reddish pinkish glow, then walk up to it with good armor and a couple shields, it will then sniff you and grab you with it's tail, when it is done grabbing you, you will be severely injured, you have 5 hours to grind xp for the queen, kill other queens for pheremone glands, and when the time comes, on the last ten seconds, eat a pheromone gland and have a cryo on you in a pen, claim it, and cryo it, when deployed, it will act normal. Now you raise it, and bam, you have a reaper.