"What if they take you along?"
another translation in English could be "and what if they come and fetch you". you must translate the idea of "what if" which is not meant in your proposed sentence.
And "qu'est-ce qu'ils te prendent" is not correct at all :
"prendent" is not a verbal form of the verb "prendre", it is "ils prennent"
"qu'est-ce qu'ils te prennent ?" would translate in : "what are they taking from you?"
in no way would I ever expect chercher to mean "take along". this seems like a colloquialism, not a direct translation
"What if they come and fetch you" and "What if they take you along" seem like very different ideas to me.
I agree and if chercher means to search or to look for how does that translate into "take along"? I'm totally confused.
I agree, it is confusing. While it may make sense to translate the French sentence with "What if they take you along?", I don't think it makes sense to give the English sentence "What if they take you along?" and expect me to come up with "Et s'ils viennent te chercher?"
fetch - they come here and collect you take you along - they depart from wherever to some certain place and you go with them (This might be an Americanism, as opposed to UK English)
I would translate their translation as "what if they come to look for you?" I too am confused by the use of "chercher" to mean "to take."