Thank you for the translation! While I think Fritz is entirely capable of inventing STDs, it makes for a more dramatic reveal if Marwitz was, in fact, plagued by them. (It also makes Fritz' actions a bit more ambiguous, which is always more interesting.) Speaking of interesting, something like this makes me realize I prefer my Heinrich characterisation recalling that being Fritz' other self also involves having his own capacity for anger, pettiness and above all retaliation, as opposed to being written solely as a victim.