Servitors are generally really powerful in the first 2 weeks. I'm not sure why, but since it's taking your personal energy, you should notice that it'll be taking plenty of energy from you, and that it's very easy to see (which is why you see it looking at you). Eventually, they figure out how to moderate their energy usage and get the most out of small amounts of energy. It's as if they're over-eager to do what you ask of them in the beginning but since they're young they don't always get something done right the first time, so they take more juice and try again, etc.
If you're very nice to your servitor and treat it nicely, meaning you say good morning, and good night, and think about it regularly or actively try to communicate with it and tell it to rest in it's home (if it has one) while it doesn't have a task to do, then it shouldn't turn on you. Giving food offerings will also help establish a loving relationship.
I don't really understand why so many mage's try to force their will on servitors and punish them for not doing something, etc. I'm not surprised to read about when they try to kill their master. Simply asking nicely is enough to get a task done quickly and easily. I have 2 that I've taken under my wing as familiars and have not had any problems. They seem to be very loyal and a great help with healing and various tasks I set for them, especially manipulating the weather. I wouldn't regret having to destroy them if I felt they were messing with me or were simply behaving badly, but for now I feel safe with them.
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