Tomarle el tiempo a alguien

[aleCcowaN]

In Argentina, when we say "le tomaron el tiempo (a alguien)" we mean they have learn that person's habits, style, way of thinking, weaknesses, etc. so the person has become predictable and so it's easy to take advantage of him or her.

How could I say that in English?

[Rusty]

"To have someone's number" immediately comes to mind. It means we can pretty well predict how someone will act, so we have the advantage.

[poli]

Another term would be, to know what makes someone tick.

Even better, you can use, to size someone up.

[aleCcowaN]

Thanks you both, Rusty and poli. Good suggestions. My only doubt is both your examples describe the same final state, but "le tomaron el tiempo" also refers to the process of reaching that result, like a thief who is getting the combination one number at a time.

Would there be a way to add to those expressions to convey the same idea?

[Rusty]

I believe 'having one's number' and 'knowing what makes one tick' both infer a process.
Any parent of a boy or a girl can say "I've got his number" or "I know what makes her tick" because the parent, over time, knows the child quite well (has pieced the child together, one puzzle piece at a time). We may arrive at the same conclusion with friends, associates, coworkers, etc., to a good degree.

To me, "sizing someone up" doesn't necessarily include a drawn-out process. It's a judgment call, a measuring stick. When we meet someone for the first time, for example, we "size them up" rather quickly, but our initial judgment usually requires tweaking as we get to know them better.

[poli]

In addition, the use of the present progressive implies the process of what makes them tick.

Also, feel someone out implies the process of covertly getting the dope on someone.

(Getting the dope on does not imply drugs; it implies information,)

[aleCcowaN]

Thanks you both. That was very complete. I need to read it again carefully a couple more times. A lot of expressions come to mind, but their boundaries don't match. I'll study it a little more before replying so this doesn't develop as an outward spiral.