Part of test block zeta.
Not much is known about Marathon as an individual.
Marathon is most likely a Human from earth invited to the test program. They claim they only came because they wanted to "call my dad". Marathon feverishly rants about a $30 prize that does not exist, they claim they've already won this prize.
Marathon appears to be a very untrustworthy individual who often contradicts themselves and claims things known to be false as true.