Mine is pretty basic.
Can they listen? Do they actually hear what you are saying and respond appropriately?
Can they apologize when appropriate? Is it a real apology, vs. blame-shifting and excuse-making?
How do they treat people of (perceived) higher social rank? (Perceived) lower social rank?
How do they react to the setting of appropriate boundaries? (I need to go now; I will be unable to see you, I've come down with the flu; Sorry, I'm already overcommitted and can't accept this assignment or request)
Is their sense of humor kind or mean? Is it based on belittling either people or groups? Do they have an unthinking, reflexive response to members of any group*?
How "turfy" are they? How often and how widely do they regard others as competitors? (Do they compulsively "one-up" everything you share? Do they withhold key information from you on the job? Etc.)
How do they respond to others' real need, or real pain?
Do they keep their promises? Do they try to dodge responsibility and dump it on you?
Are they mentally/emotionally lazy (do they think in slogans without any appraisal of those slogans and who might benefit from having people believe them? Do they expect you to figure everything out, do all the emotional work)?
These work in any setting - home, school, work, religious observance, socializing, at the doctor's office, etc. Unfortunately, there are a lot of doinks out there, so it's useful to identlfy them early.
*Serious food for thought here, about the human capacity for growth and change. Reformed (and Atoning) Former White Supremacist Christian Picciolini
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"I believe you find life such a problem because you think there are the good people and the bad people," said the man. "You're wrong, of course. There are, always and only, the bad people, but some of them are on opposite sides."
-- Terry Pratchett, Guards! Guards!