Pack mentality
Glecks are highly sociable creatures and will seek out either groups of Glecks or Searadithian families to be with.
Although it is possible to refuse the services of a Gleck, it is highly dangerous to try and force them to work for you. Most recorded attempts to contain, sell, or otherwise control the Glecks have lead to the Glecks escaping or the entire community of Glecks turning on the abusers in the night.
The lifespan of a single Gleck is 40 years, so it is not uncommon for entire generations of Glecks to be in the service of one house.