Apemantus Oldcastle only awoke to this new life a few months ago, naked in the Amedio Jungle at the base of Cauldron’s mount. After almost being taken by slavers he learned of Sasserine and made his way there — believing he has been brought here for a purpose. And that in Sasserine he shall find his Crucible to salvation.
His first stop in Sasserine, having entered via the southeastern Sunrise District, was the Shrine of Mayaheine. It is to the Paladin goddess Mayaheine that go his prayers, yet he is unsure if she listens. Indeed, he is shunned from her Shrine (building #28 in Sunrise) by Mayaheine’s Paladins. Not that that stops his entreaties to them. Hopefully they will give him some epic quest to prove his righteousness.
But Mayaheine’s Shrine is not the only place in Sasserine where one can find Apemantus Oldcastle searching for an epic quest to prove himself. On the assumption that he was purposefully reincarnated near Sasserine he has approached the Historians Guild (building #23 in Sunrise) where he has spent many days studying. There could be some clue here, some epiphany to be discerned to help him start his quest.
Likewise, in the Noble District, Apemantus Oldcastle has become friendly acquainted with Sasserine's tattoo artist and Sage of all things Planar -- Callisto. One can often find him at Callisto’s Needle, discussing the Lower Planes, Sigil, Celestia, and the Astral and Ethereal Planes (Noble District #26). Perhaps some bit of esoteric, ontological mystery will make itself known here and propel him to his quest.
Additionally, one may find Apemantus Oldcastle in Kiva Willowtop's cartography shop in the Noble District (#20). He has visited a few times, talking with the Halfling about some maps of the Amedio Jungle and any news she may have heard recently. He can't afford to buy any maps of yet, but he's at least made a bit of a friend.
Finally, one may find Apemantus Oldcastle at Sasserine’s Shrine of Liir, also in the Noble District (#2). Here he has sought out what his birthmark may mean from the goddess of poetry and art. Hoping that this icon of a small bird is an mark of goodwill, a Sign from the gods of Law and Righteousness, he has no idea that the Mockingbird is really a secret mark of Mephistopheles -- who once owned his Soul -- and hopes to again very soon.)