Personally, I'd call the person wise. Really depends on the Reason Why the person is observing others. A person gaining wisdom would most likely observe wisely, meaning the person being observed wouldn't even know, but not to the Extreme. But a person just excessively watching someone, like staring, would be uncomfortable...Basically your question is unanswerable, unless you're more Specific.
Because they are dating one person then go behind there back with another one that is why we call them cheaters.
A person who makes people happy can be referred to as a joy giver, happiness spreader, or simply a positive influence.
A person who laughs at others is typically referred to as a bully or a mocker. Their behavior can be hurtful and can negatively impact the well-being of those they are mocking.
People may call others stupid out of frustration, anger, or a desire to assert dominance. It can stem from a lack of empathy, insecurity, or a need to feel superior. Overall, name-calling like this is unproductive and harmful to relationships.
A person with a big ego can be called arrogant, conceited, or self-absorbed.
He observes what the other dogs are doing.
He observes what the other dogs are doing.
sommeone who hidding someting __ Vigilant or alert
hero
hypnotist
@ssh0le.
A zoologist
a plagiarist
A person who tortures and gets enjoyment out of it is called a sadist.
A namesake, if one person was named for the other.
A Medium
An examiner is one who tests others.