It occurred to me that Scandinavia and England can't be the only countries to have someone that was sworn to the household's owner and was basically a daily logistics/operations commander. However, a few google searches isn't turning up anything so far, and I figure I may as well ask some experts: What are some other equivalents of the norse/english Housecarl position?
Not exactly what you are asking, but here it goes.
Emperor Kang'xi of the Qing dynasty ascended the throne at the age of seven with four appointed reagents. One of the reagent named Oboi eventually seized most of the power and was the greatest threat to the emperor's rule.
What kang'xi did was gathering a number of children similar to his age and practice wrestling. Oboi thought the young emperor was only a child careless of politics. Then during one such practice, kang'xi ask oboi to watch a demonstration(other version says kang'xi asked oboi to give them tips since oboi was a renowned warrior and commander), then the boys charged in and over powered him.
Kang'xi then had him executed with the help of his grandmother and solidified his position as emperor.
Also, Alexander's Hetairoi, janissary of the ottoman and mamluks of Egypt. I know two of them were of slaves in origin but both later became a make or break force for their respected rulers.