I think Van Helsing started business about a year before Demon Hunter (because of the release dates for the skins), so maybe once they meet up he can give her some tips about the monsters she hasn’t fought yet. In return, she gives him a couple of pointers too.

ribbons-halos:

They start out at as very standoffish partners, considering that Sombra is partly demonic and McCree doesn’t trust that right off the bat. Sombra also isn’t so keen on turning her back and finding an arrow in it because McCree just had to kill the closest demon. 

So, they bicker and get on each other’s nerves a lot. They work smoothly when it comes down to chasing an evil monster, as they both have the goal in mind. So, when McCree tries to extend an olive branch by giving her a little advice about a certain monster she hasn’t faced yet, Sombra gets a little prideful. Then, when McCree struggles while going against a monster, Sombra quietly gets him her advice, which he hesitantly takes. 

The first time he uses her advice, Sombra gets a little soft, and not so hard headed. She offers to teach him more about what she knows, but only if he’ll do the same in return.