Achilles Davenport is one of the main characters of Assassin's Creed 3 and is part of the Assassin's guild. He lives alone in his run down home after the death of his wife and son. He failed to stop the Templars from strengthening their ranks, something that Connor often reminds him.
He's often bitter, dolling out life lessons. He's also extremely rational, scolding Connor when he's overcome by revenge.
Role in Assassin's Creed 3
Connor is sent to Achilles by Juno. Achilles initially refuses to help him, but Connor persists, defending Achilles's homestead. Achilles eventually takes Connor in, giving him the name of Connor which he claims was for practical reasons but it's later revealed that the renaming was in honor of Achilles' son Connor, who died at the age of seven.
Achilles tells Connor about the war between the Assassins and the Templars, telling him what's at stake. Achilles also introduces Connor to certain major figures of the rebellion and helps him assassinate key Templar figures.
Achilles warns Connor about sparing Templar lives, a lesson Connor learns the hard way when a Templar he had spared threatens his village. Achilles also gets into arguments with Connor in regards to how to approach the Templar threat. Achilles argues that, regardless of who the Templar is, he must be killed for the good of all. Achilles berates Connor on his reconciled relationship with his father and is ultimately correct in predicting that Haytham would ultimately betray Connor.
Achilles eventually dies of old age, his last piece of wisdom warning Connor about his father. Despite their rocky relationship, Connor and Achilles end up being good friends, Achilles serving as a mentor and father figure. Connor ends up hiding the precursor relic that Desmond is looking for in Achilles' grave.