I've got to admit, when I first heard of Deku x Lady Nagant, my reaction was mostly 'huh?' It felt like it came out of nowhere, especially since their actual interaction in 'My Hero Academia' was so brief and antagonistic. But the more I've seen the ship pop up, the more I've realized its appeal isn't about what is, but about what could be. It's a complete AU playground.
What grabs me isn't just a hero falling for a villain, which is common enough. It's the specific dynamic of Deku, this pure-hearted symbol of hope, being drawn to someone whose faith in the system was utterly shattered. Nagant isn't evil for evil's sake; she's a disillusioned former hero who saw the rot at the core. A story that pairs them is really exploring whether Deku's idealistic vision can survive a direct confrontation with that level of institutional corruption, or if it would fundamentally change him. Does he try to save her, or does her cynicism start to save him from his own self-destructive heroism?
The best fics I've read don't rush the romance. They build a slow, painful understanding. Maybe it starts in a prison visiting room, with Deku being the only one who keeps showing up to ask her 'why.' The tension comes from whether his empathy is a strength or a fatal flaw. I've seen versions where he uses her insider knowledge to dismantle the Hero Commission from within, making them partners in a dangerous, secret revolution. That's a far more interesting conflict than just another fight against a big bad.