I worked with someone years back who I'd describe as aggressive.
It was their way of speaking. So they'd come into the office and say something along the lines of "I'm going for lunch now and no one is to stop me."
And we'd all be looking at her thinking "no one has ever stopped or even suggested she didn't go at a particular time."
The rest of us tended to courteously say something like "okay if I go for lunch now" as we couldn't all clock off at once, but other than occasionally someone might say something like "can you check this for me before you go" no one ever objected.
It wasn't just the words, it was also the tone. What my granny would have called "with their fists up tone".
But it wasn't just that. If someone above them asked them to do something in a particular way they'd either argue the toss about their way was better (and no they weren't normally right) or say that they'd always done it the way they were being told to do it and they didn't need telling (while often in the middle of doing it clearly their way way), and that sort of thing.
It put people on edge speaking to them, even to do a simple job because they so often got this aggressive response, so they got treated with kid gloves.
When they were spoken to about this - it made working with them very difficult, they denied it and said they had never been aggressive. They then for a short time adapted a very passive aggressive manner which was nearly as bad - before resorting back to the aggressive side. They left a couple of years later and the atmosphere in the office was totally different - people weren't on edge and could relax.
So I'd say that someone can come across as aggressive without meaning to, or being aware.
OP, ask for specific examples. It may be your tone as much as the words.
I'm guessing as you want to support them, you are senior to them - at least I hope so, because otherwise support is not what you should be doing.
I'd look at whether how you go in with mistakes they've made or requests. There's a difference between "I want that report now" and "How far on you the report because I need it asap? Do you need any help?" but one can come across as aggressive.
It may be that they're being over sensitive, but I don't think it's helpful to start from that assumption.