Practice common courtesy and hospitality. A lot of times little things aren’t actually little to those who are hyper sensitive (something people struggling with depression often exhibit). If someone struggling with depression does something good for you, thank them. This is a rare case where one has a ridiculously easy opportunity to authentically build another person’s self-esteem. Another common courtesy thing is to not ignore people’s communication. Someone struggling with depression will almost always interpret being ignored as a sign they aren’t worth engaging. Practice hospitality, taking in people even when you don’t want to. Quantity of time is often more important than trying to regiment quality time because quality time tends to bubble up extemporaneously in the quantity of time. A lot of people don’t open up until the second or third hour you’ve spent talking to them. This is especially true for males.
Be compassionate instead of dismissive of depressed people’s impaired interpretive skills. Our hyperindividualistic culture puts all the burden on those struggling with depression to play cognitive tricks to smoke and mirror themselves into thinking positively. Often the effort to think positive is counterproductive because the chemicals and situations are such that the positive thoughts fall flat like darts against a brick wall. Plausible deniability is at work a lot of the time (where you are in an ambiguous situation and have to choose to believe a positive or negative interpretation). One can tell the depressed person to believe the positive interpretation or one can find peace with their thinking. If you can offer cold hard evidence that an ambiguous situation is stacked in their favor, present it. But if you can’t don’t try to talk them out of their interpretation because it will just make them double down on the negative one.
If you are being used as a shield, put up with it. Many depressed people use people, not principles as a shield against the negativity inside and around them. This is abhorrent to the therapeutic-industrial complex which is every man (and women) for themselves. But emotionally weak people need emotionally strong people, and yes it is a relationship where they will be doing more taking than giving (something else the therapeutic-industrial complex tells you to avoid). But this is one of those cases where effort on the part of the emotionally strong person helping the depressed one will do wonders for the sum total of happiness in the world even if it decreases the strong person’s happiness.