Originally Posted by Alexrd
I haven't read the books, but I was wondering if I should invest on Jaqen. Will he be a prominent character? He has become one of my favourites.
A man knows.
You may read that as I included an answer of sorts for your question and some sort of consolation prize if you don't like it.
Still a spoiler, though.
Not so far in the books. He doesn't show up much more, sadly, but his existence is ESSENTIAL for what Arya decides to do next. In a way, it's almost like she has many tutors through the story.