After giving this some thought, I think Gen would get the most out of a memory share if he could somehow grasp the magnitude of events that Emet's dealt with in the past? So something like a battlefield involving a lot of deaths, or something to show that Emet's suffered a lot of significant losses in the past would make him immediately sympathize with and also respect Emet a lot more. Since Gen's honestly close to losing his mind over just a few losses in his own life, and he'd (grudgingly) really respect that Emet manages to stay determined and sane(?) regardless. It's quite a nebulous concept, so maybe it's a bit of a high demand ... since it also doesn't have to be a single big memory, I think maybe something like a handful of quick flashes of significant events might also work, as long as you wouldn't mind!