Dangerous. What does it means? What can being called “dangerous” at all? Sitting in a house burning in flames might be dangerous. Swimming in the ocean can be as well. And a gun in your hand? It can be dangerous and can give you a feeling of safety. And what about a pretty pillow on your bed? Is it dangerous? It can be, if your partner’s desire to suffocate you with it just to avoid to broke your hyoid bone and thinking it that if he does in this way, he can avoid the punishment.
The difference between dangerous and dangerous is: how risky it is to contact with.
Even the most gentle spirit can be dangerous if you handle him wrong, or you are that kind of person who can irritate him; but harder to hit that level which would be threatening. While you can live the most safest and happiest life with a demons/gods like Andras, Sitri/Set.
The devil is in the detail. You have to know their personality, temperament, motivations, interests; but yourself, too. Because your personality and abilities can put an effect of your relationship, and things what you might experience.
You can make easy mistakes coming from your own personality, which might be absolute natural from you, and would makes Andras angry or impatient, or feel annoyed by you, for he is basically a serious, dominant, intimidate, straightforward and active entity. However, if you notice something inside you, which attracts his attention and interests, you can experience an another face of his.
It is harder to make any mistake in Lucifer’s case than Andras’ case, for they have different personality, so their reactions will be different (more likely). No doubt, you’ll feel what he wants you to feel.
He made me know about his presence. But I found out later that he is the “source”, the “cause” of this intense and unusual change around me. I don’t feel like I’m in danger, but no doubt, he awakened my inner fury, discord and beast several times, and after long months of absolute peace and balance, how could I not see it? ( I hit my own brother, which I never did before, just like that terrible and angry argue between us - no, never. But my dreams also tells a lot about his presence, however still don’t know about his exact goals, plans with me. ) His possible familiars also hanging around in my house. 
After all of these… he doesn’t seems treathening, and the way how I slowly see him, neither makes me feel in this way.
Stay respectful, serious and determined. He is a warrior, a Marquis in his “full-time”.