Assassin's storylines have never been so strong or succinct in the first place, I agree. But even so, we've had characters that have had memorable and well written motivations that go past just meeting someone nice, at least on the outset; so much so that I reckon I could easily write a bunch on most of them.

But Shay? He gas nothing that's really important to him, nothing that drives him. He has his old comrades, but never are we given that cathartic moment of frustration and betrayal poured out onto the people that deserve it. At the beginning of the game, he is shown to be a questioning person, unsure of himself and where he belongs in the world - if he's fighting for the right thing. And that attitude is only ever manifested at the start of the game. After being saved by the Templars, he never once questions their motives, their goals, their methods. He just does it because...that's what the plots premise requires him to do, and the writers are not good enough to make it convincing.

Shay has killed thousands of people (albeit unintentionally) and the only time that his guilt is actually displayed in full is as soon as it's over. Over the course of the game? Nothing. A slight mention here and there, but there are no pensive moments, no questioning of what's happened and why it's come to this. Over the course of the game we hunt old friends down one at a time. There is no emotion in any of these missions, the most we get is a 10 second goodbye for each of them. His best friend, Liam, becomes a comically moronic caricature of the enemy and there is nothing to keep us caring about him or their fight in any way. You don't care about Liam, you don't care about Shay. Things just happen because they have to happen for there to be a game. Which is exactly where this game falls in almost every aspect. Things happen, because they happen. Why make comically evil Assassins seemingly hellbent on destroying the world? Because we couldn't make a more convincing tale of ideological change and betrayal. Why showcase a character questioning his faith and methods only to completely shelve it later? Because he has to switch to facilitate the plot.

The game, and Shay as a result, is a writing clusterfuck.