This is a "Wild Mass Guess" entry, where we pull out all the sanity stops on theorizing. The regular entry on this topic is elsewhere. Please see this programme note.
Abel is a child
Abel is chosen for all these assignments because of how oblivious he could be to outside influences and how he'll probably follow orders without question. This theory at least explains why all spoken dialogue appears in Peanuts-esque trombone sounds and the slide-whistle that occurs when lifting up his mission briefing card.
The man at the end of the first mission is the ex-husband of the woman at the end of the second
This is hinted at by the similar hair colour, and the unrequited love is further cemented by the book you see her reading in mission 2.