  We consider tit-for-tat dynamics in production markets, where there is a set
of $n$ players connected via a weighted graph. Each player $i$ can produce an
eponymous good using its linear production function, given as input various
amounts of goods in the system. In the tit-for-tat dynamic, each player $i$
shares its good with its neighbors in fractions proportional to how much they
helped player $i$'s production in the last round.
  Our contribution is to characterize the asymptotic behavior of the dynamic as
a function of the graph structure, finding that the fortune of a player grows
in the long term if and only if the player has a good self loop (i.e. the
player works well alone) or works well with at least one other player. We also
consider a generalized damped update, where the players may update their
strategies with different speeds, and obtain a lower bound on their rate of
growth by identifying a function that gives insight into the behavior of the
dynamical system.
  The model can capture circular economies, where players use each other's
products, and organizational partnerships, where fostering long-term growth of
an organization hinges on creating relationships in which reciprocal exchanges
between the agents in the organization are paramount.
