You, an assassin, run for your life as you try to bring the manuscript back to the Brotherhood. But suddenly Shay comes darting out of a side alley and rams you so that you hit the ground hard

Shay and you were pretty close when he was still serving the Brotherhood. But after the Lisbon incident, he also developed a hatred for you. You actually thought he was dead after you saw him fall down the cliff with your own eyes. but here he stands alive before you... a Templar