Before a first one-on-one with a new manager, most people prepare the same way, they think about what they want to say. Almost nobody spends that same time finding out how the person across the table actually operates, and the fastest way to learn that is rarely asking them directly.
Why asking directly gets you the polished answer
Ask someone how they like feedback delivered, or what they actually reward in a meeting, and you get the version of themselves they believe, or want you to believe. That is not dishonesty. Most people do not have precise, accurate insight into their own patterns under pressure. The people who have already worked alongside them do.
What recruiters already do about this
Executive recruiting has a name for the workaround, the back channel reference, quietly checking with former colleagues a candidate did not put forward themselves, rather than relying only on the curated list handed over. Recruiting guides describe these as often more balanced than official references, precisely because nobody selected those specific people to make an impression. It is also a genuinely debated practice on fairness grounds, worth taking seriously rather than skipping past.
Where the line sits
This is not license to quietly build a file on someone before you have even met them. Done well, it stays narrow and respectful, informing yourself before a high stakes first meeting, not collecting ammunition. The recruiting version works the same way, used with some transparency and to add to a direct read, not replace one.
Where to start
Before your first real meeting with a new manager or a stakeholder you will depend on, find one person who has already worked alongside them and ask something specific, not what are they like, but a narrow, concrete question, how do they prefer to receive pushback, what actually lands well with them in a meeting.
A specific question gets a specific, useful answer. A vague one just gets gossip.
Knowing exactly who is worth asking, and how candid they are likely to actually be with you, is a judgment only you can make once you know your own workplace. What this gives you is the kind of question that tends to produce something you can actually use, instead of a vague character sketch.
There is a particular way to ask this that does not read as digging for dirt, and it is worth having ready before the meeting where it would actually help.