game of thrones - How did Jaqen H'ghar get caught?

Following a recent 9gag post:

Did Jaqen H'ghar end up in that cage because he knew that he would meet and "recruit" Arya, or was it some strange coincidence? Is it described somewhere in the books, or left unexplained?

Answer

It is not explained in the books, but there is mention of him in AFFC, I believe, when a prison guard mentions that there were three men in the black cells. Ned Stark gave Yoren the pick of the dungeons, which included those three, and presumably Jaqen.

The fan speculation that Jaqen is Syrio Forel is based mostly on wishful thinking, as there is no evidence of that, other than the fact that Syrio might have been captured and Jaqen appears in the black cells at around the same time. And also because he knew Arya's real identity. But like I said above, I believe Jaqen was already in the dungeons when Ned was Hand.

On that note, on the forums of Westeros.org, it has become somewhat of a meme that everyone is Syrio Forel or Jaqen H'ghar. So there are many theories, most of them probably not true.

One theory connected Jaqen with the death of Balon Greyjoy, combined with the prophecy from the Ghost of High Heart:

I dreamt of a man without a face, waiting on a bridge that swayed and swung. On his shoulder perched a drowned crow with seaweed hanging from his wings.

This is likely a faceless man, sent by Euron Greyjoy to push Balon off the bridge described in an early Theon chapter. But I find it unlikely that it would be Jaqen.

I also highly doubt that Jaqen got himself thrown in the black cells on purpose. It is hard to assassinate people while locked up and in chains. A reasonable theory is that he was caught during a mission.

The observant readers will notice that Jaqen's story continues in the books.

In the prologue of AFFC, an alchemist is seen to murder the POV character, and his physical description matches that of Jaqen after he changed his appearance in front of Arya at Harrenhal. Apparently, Jaqen wanted access to the Citadel, for some as of yet undisclosed reason.

It is clear that something is up with Jaqen, but as of yet, we do not know what.