Butcher and Kessler:
Thinking about it, the Panjshir Valley mission might have been more than the '11 years ago' Kessler mentions - he says that's when Billy last saw him but 'strictly speaking none of that shitshow ever happened' or something, which actually really might be a hint that it's something Billy's brain's making up to convince him Kessler survived Panjshir. So Kessler's death might have come before that, and might even have been pre-Becca. But it still suggests Billy was doing work where he might have met Kessler again 11 years before that scene, which would put it firmly in the era where he was with Becca or right after she left (in as much as the timeline ever makes sense). Which means he was in the army/CIA/Special Ops when he was with her? Or it truly did happen after Grace recruited him, during his 'training' for supe-hunting?
And then there's the scar, which memory/psychic-Kessler said he gave Billy on their last mission together, and which people point out isn't in the flashbacks with Becca.
??
I should stop trying to work it out and just make up whatever I want. Which seems to be how the professionally-written show worked
It's very funny that it was actually Billy's 'worst side' that was making fun of him coming up with the codename "The Boys", and that Billy looked so insulted by it
