If you're hunting down those specific pairings, honestly, the search can get a little dusty. Those two don't get thrown together as often as some of the more mainstream ships, which kinda makes any decent find feel like a secret handshake. I stumbled on one a while back called 'Parallax' over on Ao3—completely forgot the author's handle, sorry. It was this slow, messed-up thing where they were both agents from rival factions forced into a temporary alliance. The dialogue had this sharp, paranoid edge I really dug; it wasn't about romance so much as two deeply broken people figuring out if they could even trust each other without getting shot. More about the tension than the payoff, which worked for me.
Word of warning though, a lot of the older fics for them are buried in archives or live on sites that look like they haven't been updated since 2008. The tagging on Ao3 is your lifeline—check the crossovers and the '&' relationship tag alongside the '/' one, sometimes the best dynamic stuff is hiding there as a subplot in a bigger ensemble story. I've clicked on a few that promised the pairing but it was barely a mention, total bait-and-switch. 'Parallax' was the only one that really stuck with me as being wholly dedicated to that specific, fractious energy.