So I went back to watch the AC II Linage video after reading ~LadyVe's story about Giovanni and Maria because their interactions with eachother melts my heart. Anyway, I'm watching it and it gets to the part where Medici and another man are asking Giovanni what he has heard. I look at the unnamed guy and all of a sudden my brain decides to kick in and work! I literally jump in my seat and point at the screen and said, "Oh my gawd! It's the Templar that betrays Giovanni and has him hanged!!! I can't believe I didn't realize it sooner! I feel like an Assassin's Creed idiot now ! Ah, at least I did figure it out and now I know who is responsible for turning traitor on Giovanni. Want to see a comparison? Check out this [link]
(sorry for having to link it, I couldn't figure out how to post pics to the journal)

Also, here is some food for thought that also popped in my head (not that I necessarily believe it myself, just some fun conspiricay theory).
Has anyone compared Uncle Mario to Al Mualim? Could he possibly betray Ezio like Al Mualim betrayed Altair? I don't know which of the brothers, Mario or Giovanni, is older but could it be that Mario, out of jealousy for being passed over as "the favored son/master assassin" because he doesn't have the same power as Giovanni (like say, Eagle Vision to read Altair's codex) so he uses Ezio to run and do his errands/dirty work like Al Mualim did to Altair only to then stab him in the back? Could that explain why he didn't come to his brother's rescue?
Also, (and it is a reach just like the rest of this hypothesis) if you look at Al Mualim and Uncle Mario they both have an injured eye. Granted the injury is to opposite eyes, but it is still there like a mirror image.
Finally, I looked up the name Mario and what it means. The baby name book I saw it in translated Mario as Uncertian, bitter.
How curious!
Here is a [link] if you want to see them side by side.



EDIT
Did anyone else notice this or is it just me? We all give the main assassin men of Assassin's Creed nicknames like Alty, Ezi and Desi? Now, look at Desmond's nickname...Desi. And who helps him escape? Lucy. Lucy and Desi like in "I Love Lucy". I hope the Ubisoft team didn't do that on purpose!!!