Jaqen H'ghar

Jaqen is part of the caravan Yoren leads out of King's Landing toward the Wall, made up of recruits and prisoners taken from the city's dungeons. He is one of three men pulled from the black cells of the Red Keep, kept for the most dangerous criminals; the other two, Rorge and Biter, fear him and never cross him. Chained alongside them, he is courteous toward Arya Stark, who travels hidden among the recruits.

When Ser Amory Lorch's men attack by night the ruined holdfast where they've taken shelter, the fire reaches the wagon where he is chained. Arya throws them an axe to break their chains, and the three escape on their own; soon after, they join the Bloody Mummers as sellswords.

Now a sellsword, Jaqen runs into Arya again at Harrenhal and tells her he owes her three deaths, one for each life she took from the Red God the night of the fire. Arya names Chiswyck, one of Ser Gregor Clegane's men, and Weese, the keeper of the castle's servants.

She wants to spend the third name freeing the northern prisoners loyal to her brother Robb, but Jaqen refuses: that war isn't his. So Arya names Jaqen himself. Bound by his own rule, he cannot refuse — and offers her another way out: if she helps him free those prisoners and take the castle, the debt is settled.

The bargain kept, he decides Jaqen H'ghar must die: he passes a hand across his face and his appearance changes, now a hooked nose, a scar, a gold tooth, and black curly hair — whether a new disguise or his true face, no one can say. He gives Arya a worthless-looking coin and tells her that if she ever needs help, she should give it to any man of Braavos with the words "valar morghulis".

Some time later in Oldtown, a man claiming to be an alchemist, matching the description of Jaqen's new face, is said to kill Pate, a novice of the Citadel. Shortly after, someone calling himself Pate presents himself to Samwell Tarly when he arrives in the city — leaving open the possibility that it is Jaqen wearing that face.