Chatter in another journal, about friendship, being a good friend, and not being a drag on one's friends, brought me to an interesting idea: that the safety and quality of a relationship should be lined up against Maslow's Hierarchy of Needs to see how the friendship fulfills the needs (sometimes), or (more interestingly) to make sure that the relationship does not pose a threat to the needs.
It is in fact a pretty decent checklist for evaluating the basic safety of a relationship, starting with the most basic level.
1) Physiological: breathing, food, water, sleep, homeostasis, excretion, (and sex).
Does this person attempt to deny me reasonable access to air, food, water, sleep, and the bathroom? Does this person cause me physical injury?
Sex is a little bit different; there is no reasonable way to declare that the hot individual that you just met in a bar is denying you access to sex on a basic-needs level when they won't get in bed with you. However, if there is a person/organization/medication in your life that is preventing you from any sexual fulfillment (assuming a consenting adult partner and/or time by yourself), seriously consider the impact that is having on your life. If someone is getting in the way of your having the basics for survival, it doesn't matter if they're the best creative partner ever, if they're in a position where they can also interfere with your life on this level, it's time to do some serious re-evaluation.
A certain amount of support on this level is sort of assumed for the purposes of being a decent human being if it's within one's reasonable power to grant, like not waking someone up for frivolous purposes if they've just gotten to sleep, or giving someone a glass of water if they're thirsty (assuming this isn't an emergency survival situation like everybody is lost in the desert). "Not being an axe-murderer" is a requirement at this level.
2) Safety: security of the body, of employment, of resources, of morality, of the family, of health, of property.
Does this person put me in physical danger, put me in danger of losing my job, steal my possessions, jeopardize my health, deny me reasonable access to available resources, try to make me act in ways that are against my moral code, and/or do the same (or deny access to anything on Level 1) to members of my family? If some dickhead is trying to get me fired, or is deliberately waking my sister up when she's trying to sleep, this doesn't say good things for our future as friends, even if they're not actually an axe-murderer. Again, basic aid with these things is in the being-a-decent-human-being category. If someone is bleeding, provide first aid and/or alert someone who can provide it. If someone is about to step on a banana peel, tell them.
3) Love/Belonging: friendship, family, sexual intimacy.
Does this person try to separate me from my friends, alienate my family when I'm trying to maintain contact with them, promise me sexual intimacy and then deny it, interfere with my attempts to seek sexual intimacy with a consenting adult partner? This is getting into classical this-is-an-abusive-relationship checklist material, which means that it's not things that people necessarily take for granted as rights. Aid in stuff like this is a little above-and-beyond in many cases, but basic "I'm sorry to hear your mom died" is still general social decency.
4) Esteem: self-esteem, confidence, achievement, respect of others, respect by others.
Does this person attack your self-esteem, offer destructive criticism, take credit for things that you have worked on without acknowledging you, not acknowledge things that you have worked hard on, treat you dismissively, make a point of pointing out the human failings of people you hold in high esteem (particularly by singling them out for criticism and ignoring the equal or greater flaws of others), put you down to people who like and respect you? These are also on the classical this-is-an-abusive-relationship checklist, but verge into the "wow, they're a dick in general" area, because it's possible to be nasty in these areas without having a close relationship or actively endangering someone's well-being. Aid in this is getting into the friendly, going-out-of-your-way-to-be-nice territory.
It's possible to be friends with people who don't provide active support on this level, although some people would classify this as more "acquaintances", depending. Active support can be anything from a casual "Hey, nice job on that" to a serious one-on-one self-esteem booster session.
5) Self-actualization: morality, creativity, spontaneity, problem solving, lack of prejudice, acceptance of facts.
I would consider it possible to be friends with someone who has wildly different perspectives on a number of points of self-actualization, so long as there is mutual respect for the other's perspective and well-being. It's possible to believe that something is the only possible way for you personally to see things, but acknowledge that someone else can see it differently, and perhaps even thrive with a different viewpoint and do badly with your own viewpoint. This can be on issues both small and large. Someone who thinks that Star Wars is better than Star Trek can still be friends with someone who believes the opposite, and they can both be friends with someone who thinks that Babylon 5 pwns all. Other things are a lot harder to reach common ground on, like the sort of co-worker who believes that interracial dating is bad and wrong, although they're a great person in many other respects. It's possible to question someone else's choices in self-actualization without attacking, especially as there is so much room for differences of opinion that do not result in a loss of physical and/or emotional safety for either party.