Most advice about difficult coworkers assumes you need to fix the relationship. Usually you just need to manage it well enough that it stops draining you every day.
Before doing anything else, it's worth getting specific about what kind of difficult you're actually dealing with, because the right response is different for each. Someone who's abrasive but genuinely reliable and honest is a different problem than someone who's pleasant but unreliable, and both are different from someone who's actively undermining you. Treating all three the same way, usually with the same polite avoidance, tends to leave the real problem unaddressed.
For someone who's just blunt or short in a way that reads as difficult but isn't actually malicious, the most effective move is often the simplest: adjust how you deliver things to them without changing what you expect back. Some people are difficult because their communication style clashes with yours, not because their character is the problem. Meeting them with less small talk and more direct requests can dissolve friction that felt personal but wasn't.
Instead of a long, context-heavy message to someone known for terse replies: "Need your sign-off on the budget by Thursday. Two line items flagged in yellow, everything else is unchanged from last quarter." Matching their style often gets you a faster, warmer response than trying to draw them into yours.
For someone whose difficulty is really about unreliability or inconsistency, saying one thing and doing another, the fix isn't a personality adjustment, it's structure. Put agreements in writing after conversations, confirm deadlines explicitly, and don't rely on memory of a verbal commitment when the pattern suggests it won't hold. This isn't about catching them out; it's about protecting the work from a pattern you've already observed.
The hardest category is someone who's genuinely working against you, taking credit that isn't theirs, undermining you to others, or being inconsistent specifically when it benefits them. Here, the instinct to avoid conflict tends to make things worse over time, not better. Naming the specific behavior directly, calmly, and in private is usually more effective than either confronting it publicly or quietly absorbing it. "I noticed the client presentation credited you for the analysis I put together, can you help me understand what happened there?" opens a real conversation instead of letting resentment build silently.
One thing worth accepting: not every difficult relationship resolves into a good one, and that's fine. The goal isn't friendship. It's a working relationship stable enough that the friction doesn't consume energy that belongs somewhere else. Some people you'll never fully warm to, you can still work with them well.