
Basically, the courier company that MC
used was also running an illegal drug business by hiding drugs inside coffee bean sacks. Seme gave MC a bunch of paychecks 'for the coffee beans' to test him out (because if MC had accepted, that would've meant that MC was involved with the drug trafficking). It was logical to suspect MC since running a cafe in the country side really does seem like the perfect front for a drug business. MC doesn't know what's going on but he quickly realizes that something's suspicious and refuses the money. Seme thinks MC is smart. And the rest... pretty self explanatory.

Cale: I don't [actively changes events in the storyline even when he doesn't really need to] really want to [breaks into a heavily protected evil villain lair to save a dragon] get involved [secretly tells Taylor about some secret miracle medicine] I just [runs off to make an oath of death with choi han] want to be a slacker for the rest of my life [insert all his many, many, near death experiences in the future because Cale's unreliable narrator ass is too good to ignore shit when he can do something about it]
the only relationship between mir and MC will be that of parent and child, don't worry.