He is a survivor residing within the Fishermen's Village. Following the completion of the mains story quest Pact With Rais, Tobias can be found inside the Flippin' Fish shack in which strives to craft the most effective weapon against the infected.
He can later be found within another workshop located in Old Town, where he continues to provide challenges. Following their completion he provides Crane with a reward and remains at his workshop as a trader.
Despite his name, Tobias appears to have an Eastern European accent.
There is a strange oversight or bug in Tobias' first radio conversation with Crane upon his arrival in Old Town. Tobias will let Crane know that he requires Crane's help with testing more weapons, but his voice will have no radio noise attached. It will be completely unfiltered as if Tobias is standing right next to Crane, instead of over the radio through static.